LinuxLists.cc - [PATCH 00/11] drm: Restore helper usability

[permalink] [raw]

Subject: [PATCH 11/11] Revert "drm/display: Make all helpers visible and switch to depends on"

This reverts commit d674858ff979550a0e97b4ac766f2640f0d9d7e7, as helper
code should always be selected by the driver that needs it, for the
convenience of the final user configuring a kernel.

The user who configures a kernel should not need to know which helpers
are needed for the driver he is interested in. Making a driver depend
on helper code means that the user needs to know which helpers to enable
first, which is very user-unfriendly.

Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/gpu/drm/display/Kconfig | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index c77e7f85bd674dc9..864a6488bfdf1499 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -1,21 +1,20 @@
# SPDX-License-Identifier: MIT

config DRM_DISPLAY_HELPER
- tristate "DRM Display Helpers"
+ tristate
depends on DRM
help
DRM helpers for display adapters.

config DRM_DISPLAY_DP_AUX_BUS
- tristate "DRM DisplayPort AUX bus support"
+ tristate
depends on DRM
depends on OF || COMPILE_TEST

config DRM_DISPLAY_DP_AUX_CEC
bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
- depends on DRM
- depends on DRM_DISPLAY_HELPER
- depends on DRM_DISPLAY_DP_HELPER
+ depends on DRM && DRM_DISPLAY_HELPER
+ select DRM_DISPLAY_DP_HELPER
select CEC_CORE
help
Choose this option if you want to enable HDMI CEC support for
@@ -25,24 +24,23 @@ config DRM_DISPLAY_DP_AUX_CEC
that do support this they often do not hook up the CEC pin.

config DRM_DISPLAY_DP_AUX_CHARDEV
- bool "DRM DisplayPort AUX Interface"
- depends on DRM
- depends on DRM_DISPLAY_HELPER
- depends on DRM_DISPLAY_DP_HELPER
+ bool "DRM DP AUX Interface"
+ depends on DRM && DRM_DISPLAY_HELPER
+ select DRM_DISPLAY_DP_HELPER
help
Choose this option to enable a /dev/drm_dp_auxN node that allows to
read and write values to arbitrary DPCD registers on the DP aux
channel.

config DRM_DISPLAY_DP_HELPER
- bool "DRM DisplayPort Helpers"
+ bool
depends on DRM_DISPLAY_HELPER
help
DRM display helpers for DisplayPort.

config DRM_DISPLAY_DP_TUNNEL
- bool "DRM DisplayPort tunnels support"
- depends on DRM_DISPLAY_DP_HELPER
+ bool
+ select DRM_DISPLAY_DP_HELPER
help
Enable support for DisplayPort tunnels. This allows drivers to use
DP tunnel features like the Bandwidth Allocation mode to maximize the
@@ -62,13 +60,13 @@ config DRM_DISPLAY_DP_TUNNEL_STATE_DEBUG
If in doubt, say "N".

config DRM_DISPLAY_HDCP_HELPER
- bool "DRM HDCD Helpers"
+ bool
depends on DRM_DISPLAY_HELPER
help
DRM display helpers for HDCP.

config DRM_DISPLAY_HDMI_HELPER
- bool "DRM HDMI Helpers"
+ bool
depends on DRM_DISPLAY_HELPER
help
DRM display helpers for HDMI.
--
2.34.1

2024-04-22 10:36:02

[permalink] [raw]

Subject: [PATCH 07/11] Revert "drm: Switch DRM_DISPLAY_DP_HELPER to depends on"

This reverts commit 0323287de87d7e6e9c22c57d7440aa353a2298d0, as helper
code should always be selected by the driver that needs it, for the
convenience of the final user configuring a kernel.

The user who configures a kernel should not need to know which helpers
are needed for the driver he is interested in. Making a driver depend
on helper code means that the user needs to know which helpers to enable
first, which is very user-unfriendly.

Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/gpu/drm/Kconfig | 2 +-
drivers/gpu/drm/amd/amdgpu/Kconfig | 2 +-
drivers/gpu/drm/bridge/Kconfig | 10 +++++-----
drivers/gpu/drm/bridge/analogix/Kconfig | 6 +++---
drivers/gpu/drm/bridge/cadence/Kconfig | 2 +-
drivers/gpu/drm/display/Kconfig | 1 -
drivers/gpu/drm/exynos/Kconfig | 2 +-
drivers/gpu/drm/i915/Kconfig | 2 +-
drivers/gpu/drm/mediatek/Kconfig | 2 +-
drivers/gpu/drm/msm/Kconfig | 2 +-
drivers/gpu/drm/nouveau/Kconfig | 2 +-
drivers/gpu/drm/panel/Kconfig | 8 ++++----
drivers/gpu/drm/radeon/Kconfig | 2 +-
drivers/gpu/drm/rockchip/Kconfig | 4 ++--
drivers/gpu/drm/tegra/Kconfig | 2 +-
drivers/gpu/drm/xe/Kconfig | 2 +-
drivers/gpu/drm/xlnx/Kconfig | 2 +-
17 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 959b19a0410188d9..33792ca3eeb7ae8d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -75,11 +75,11 @@ config DRM_KUNIT_TEST_HELPERS
config DRM_KUNIT_TEST
tristate "KUnit tests for DRM" if !KUNIT_ALL_TESTS
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on KUNIT
depends on MMU
select DRM_BUDDY
+ select DRM_DISPLAY_DP_HELPER
select DRM_EXEC
select DRM_EXPORT_FOR_TESTS if m
select DRM_GEM_SHMEM_HELPER
diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig b/drivers/gpu/drm/amd/amdgpu/Kconfig
index ba09121e7debb247..cf931b94a1889746 100644
--- a/drivers/gpu/drm/amd/amdgpu/Kconfig
+++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
@@ -3,12 +3,12 @@
config DRM_AMDGPU
tristate "AMD GPU"
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on MMU
depends on PCI
depends on !UML
select FW_LOADER
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDMI_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_KMS_HELPER
diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index ad38cd201b006251..6015e2e4c2f620cf 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -93,9 +93,9 @@ config DRM_FSL_LDB
config DRM_ITE_IT6505
tristate "ITE IT6505 DisplayPort bridge"
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_KMS_HELPER
select EXTCON
@@ -226,9 +226,9 @@ config DRM_PARADE_PS8622
config DRM_PARADE_PS8640
tristate "Parade PS8640 MIPI DSI to eDP Converter"
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select DRM_MIPI_DSI
select DRM_PANEL
@@ -312,9 +312,9 @@ config DRM_TOSHIBA_TC358764

config DRM_TOSHIBA_TC358767
tristate "Toshiba TC358767 eDP bridge"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select REGMAP_I2C
select DRM_MIPI_DSI
@@ -335,9 +335,9 @@ config DRM_TOSHIBA_TC358768

config DRM_TOSHIBA_TC358775
tristate "Toshiba TC358775 DSI/LVDS bridge"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select REGMAP_I2C
select DRM_PANEL
@@ -381,9 +381,9 @@ config DRM_TI_SN65DSI83
config DRM_TI_SN65DSI86
tristate "TI SN65DSI86 DSI to eDP bridge"
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select REGMAP_I2C
select DRM_PANEL
diff --git a/drivers/gpu/drm/bridge/analogix/Kconfig b/drivers/gpu/drm/bridge/analogix/Kconfig
index 9659df6718de6db4..ec98c94535736c0a 100644
--- a/drivers/gpu/drm/bridge/analogix/Kconfig
+++ b/drivers/gpu/drm/bridge/analogix/Kconfig
@@ -1,10 +1,10 @@
# SPDX-License-Identifier: GPL-2.0-only
config DRM_ANALOGIX_ANX6345
tristate "Analogix ANX6345 bridge"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
select DRM_ANALOGIX_DP
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select REGMAP_I2C
help
@@ -15,9 +15,9 @@ config DRM_ANALOGIX_ANX6345

config DRM_ANALOGIX_ANX78XX
tristate "Analogix ANX78XX bridge"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
select DRM_ANALOGIX_DP
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select REGMAP_I2C
help
@@ -34,9 +34,9 @@ config DRM_ANALOGIX_ANX7625
tristate "Analogix Anx7625 MIPI to DP interface support"
depends on DRM
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_MIPI_DSI
help
diff --git a/drivers/gpu/drm/bridge/cadence/Kconfig b/drivers/gpu/drm/bridge/cadence/Kconfig
index 3480fd4d0a5f76e4..20143afded40e437 100644
--- a/drivers/gpu/drm/bridge/cadence/Kconfig
+++ b/drivers/gpu/drm/bridge/cadence/Kconfig
@@ -23,9 +23,9 @@ endif

config DRM_CDNS_MHDP8546
tristate "Cadence DPI/DP bridge"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_KMS_HELPER
select DRM_PANEL_BRIDGE
diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index 9801f47a3704530d..0cd4396914224226 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -39,7 +39,6 @@ config DRM_DISPLAY_DP_AUX_CHARDEV
config DRM_DISPLAY_DP_HELPER
bool "DRM DisplayPort Helpers"
depends on DRM_DISPLAY_HELPER
- default y
help
DRM display helpers for DisplayPort.

diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
index 6a26a0b8eff2c021..4b0183bf221c8bb2 100644
--- a/drivers/gpu/drm/exynos/Kconfig
+++ b/drivers/gpu/drm/exynos/Kconfig
@@ -67,9 +67,9 @@ config DRM_EXYNOS_DSI
config DRM_EXYNOS_DP
bool "Exynos specific extensions for Analogix DP driver"
depends on DRM_EXYNOS_FIMD || DRM_EXYNOS7_DECON
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
select DRM_ANALOGIX_DP
+ select DRM_DISPLAY_DP_HELPER
default DRM_EXYNOS
select DRM_PANEL
help
diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index dbde4e29d93a79dc..43183a68a09557b7 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -2,7 +2,6 @@
config DRM_I915
tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics"
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on X86 && PCI
depends on !PREEMPT_RT
@@ -12,6 +11,7 @@ config DRM_I915
# the shmem_readpage() which depends upon tmpfs
select SHMEM
select TMPFS
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_DISPLAY_HDMI_HELPER
select DRM_KMS_HELPER
diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
index 6caab8d4d4e0f5f8..2add54486ac4ab11 100644
--- a/drivers/gpu/drm/mediatek/Kconfig
+++ b/drivers/gpu/drm/mediatek/Kconfig
@@ -23,10 +23,10 @@ config DRM_MEDIATEK
config DRM_MEDIATEK_DP
tristate "DRM DPTX Support for MediaTek SoCs"
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on DRM_MEDIATEK
select PHY_MTK_DP
+ select DRM_DISPLAY_DP_HELPER
help
DRM/KMS Display Port driver for MediaTek SoCs.

diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
index f7708590583e7377..28a898722ace789b 100644
--- a/drivers/gpu/drm/msm/Kconfig
+++ b/drivers/gpu/drm/msm/Kconfig
@@ -6,7 +6,6 @@ config DRM_MSM
depends on COMMON_CLK
depends on DRM
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on IOMMU_SUPPORT
depends on QCOM_AOSS_QMP || QCOM_AOSS_QMP=n
@@ -17,6 +16,7 @@ config DRM_MSM
select IOMMU_IO_PGTABLE
select QCOM_MDT_LOADER if ARCH_QCOM
select REGULATOR
+ select DRM_DISPLAY_DP_HELPER
select DRM_EXEC
select DRM_KMS_HELPER
select DRM_PANEL
diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig
index 7cc305b2826d6abc..5ac852b816db262b 100644
--- a/drivers/gpu/drm/nouveau/Kconfig
+++ b/drivers/gpu/drm/nouveau/Kconfig
@@ -2,12 +2,12 @@
config DRM_NOUVEAU
tristate "Nouveau (NVIDIA) cards"
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on PCI
depends on MMU
select IOMMU_API
select FW_LOADER
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDMI_HELPER
select DRM_KMS_HELPER
select DRM_TTM
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index ab67789e59a2e7a6..ed7949bebad812c9 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -545,10 +545,10 @@ config DRM_PANEL_RAYDIUM_RM68200
config DRM_PANEL_RAYDIUM_RM692E5
tristate "Raydium RM692E5-based DSI panel"
depends on BACKLIGHT_CLASS_DEVICE
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on DRM_MIPI_DSI
depends on OF
+ select DRM_DISPLAY_DP_HELPER
help
Say Y here if you want to enable support for Raydium RM692E5-based
display panels, such as the one found in the Fairphone 5 smartphone.
@@ -572,10 +572,10 @@ config DRM_PANEL_SAMSUNG_ATNA33XC20
tristate "Samsung ATNA33XC20 eDP panel"
depends on BACKLIGHT_CLASS_DEVICE
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
depends on PM
+ select DRM_DISPLAY_DP_HELPER
help
DRM panel driver for the Samsung ATNA33XC20 panel. This panel can't
be handled by the DRM_PANEL_SIMPLE driver because its power
@@ -812,11 +812,11 @@ config DRM_PANEL_EDP
tristate "support for simple Embedded DisplayPort panels"
depends on BACKLIGHT_CLASS_DEVICE
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
depends on PM
select VIDEOMODE_HELPERS
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
help
DRM panel driver for dumb eDP panels that need at most a regulator and
@@ -891,10 +891,10 @@ config DRM_PANEL_TRULY_NT35597_WQXGA
config DRM_PANEL_VISIONOX_R66451
tristate "Visionox R66451"
depends on BACKLIGHT_CLASS_DEVICE
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on DRM_MIPI_DSI
depends on OF
+ select DRM_DISPLAY_DP_HELPER
help
Say Y here if you want to enable support for Visionox
R66451 1080x2340 AMOLED DSI panel.
diff --git a/drivers/gpu/drm/radeon/Kconfig b/drivers/gpu/drm/radeon/Kconfig
index 18c867219a706a17..07d330450f05f899 100644
--- a/drivers/gpu/drm/radeon/Kconfig
+++ b/drivers/gpu/drm/radeon/Kconfig
@@ -4,11 +4,11 @@ config DRM_RADEON
tristate "ATI Radeon"
depends on AGP || !AGP
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on PCI
depends on MMU
select FW_LOADER
+ select DRM_DISPLAY_DP_HELPER
select DRM_KMS_HELPER
select DRM_SUBALLOC_HELPER
select DRM_TTM
diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
index 4b49a14758fe0412..b72c0bbf346da5fa 100644
--- a/drivers/gpu/drm/rockchip/Kconfig
+++ b/drivers/gpu/drm/rockchip/Kconfig
@@ -35,9 +35,9 @@ config ROCKCHIP_VOP2

config ROCKCHIP_ANALOGIX_DP
bool "Rockchip specific extensions for Analogix DP driver"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on ROCKCHIP_VOP
+ select DRM_DISPLAY_DP_HELPER
help
This selects support for Rockchip SoC specific extensions
for the Analogix Core DP driver. If you want to enable DP
@@ -45,9 +45,9 @@ config ROCKCHIP_ANALOGIX_DP

config ROCKCHIP_CDN_DP
bool "Rockchip cdn DP"
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on EXTCON=y || (EXTCON=m && DRM_ROCKCHIP=m)
+ select DRM_DISPLAY_DP_HELPER
help
This selects support for Rockchip SoC specific extensions
for the cdn DP driver. If you want to enable Dp on
diff --git a/drivers/gpu/drm/tegra/Kconfig b/drivers/gpu/drm/tegra/Kconfig
index bb6e35261f1144b1..e0385d175ec6d266 100644
--- a/drivers/gpu/drm/tegra/Kconfig
+++ b/drivers/gpu/drm/tegra/Kconfig
@@ -5,9 +5,9 @@ config DRM_TEGRA
depends on COMMON_CLK
depends on DRM
depends on DRM_DISPLAY_DP_AUX_BUS
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDMI_HELPER
select DRM_KMS_HELPER
select DRM_MIPI_DSI
diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
index 02da2faf5ae33bdb..be29e5cd5215e842 100644
--- a/drivers/gpu/drm/xe/Kconfig
+++ b/drivers/gpu/drm/xe/Kconfig
@@ -3,7 +3,6 @@ config DRM_XE
tristate "Intel Xe Graphics"
depends on (m || (y && KUNIT=y))
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on MMU
depends on PCI
@@ -18,6 +17,7 @@ config DRM_XE
select DRM_KUNIT_TEST_HELPERS if DRM_XE_KUNIT_TEST != n
select DRM_PANEL
select DRM_SUBALLOC_HELPER
+ select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HDCP_HELPER
select DRM_DISPLAY_HDMI_HELPER
select DRM_MIPI_DSI
diff --git a/drivers/gpu/drm/xlnx/Kconfig b/drivers/gpu/drm/xlnx/Kconfig
index 41d753b14ccd9574..7a14a8c2e7be9e59 100644
--- a/drivers/gpu/drm/xlnx/Kconfig
+++ b/drivers/gpu/drm/xlnx/Kconfig
@@ -4,12 +4,12 @@ config DRM_ZYNQMP_DPSUB
depends on COMMON_CLK
depends on DMADEVICES
depends on DRM
- depends on DRM_DISPLAY_DP_HELPER
depends on DRM_DISPLAY_HELPER
depends on OF
depends on PHY_XILINX_ZYNQMP
depends on XILINX_ZYNQMP_DPDMA
select DMA_ENGINE
+ select DRM_DISPLAY_DP_HELPER
select DRM_GEM_DMA_HELPER
select DRM_KMS_HELPER
select GENERIC_PHY
--
2.34.1

2024-04-22 10:41:53

[permalink] [raw]

Subject: [PATCH 03/11] Revert "drm/bridge: dw-hdmi: Make DRM_DW_HDMI selectable"

This reverts commit 0209df3b4731516fe77638bfc52ba2e9629c67cd, as the
commit it fixes (which is BTW not the commit in the Fixes: tag!) will be
reverted, too.

Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/gpu/drm/bridge/synopsys/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/Kconfig b/drivers/gpu/drm/bridge/synopsys/Kconfig
index 1252fd30d4a4b461..387f5bd86089fb5c 100644
--- a/drivers/gpu/drm/bridge/synopsys/Kconfig
+++ b/drivers/gpu/drm/bridge/synopsys/Kconfig
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
config DRM_DW_HDMI
- tristate "Synopsys Designware HDMI TX Controller"
+ tristate
depends on DRM_DISPLAY_HDMI_HELPER
depends on DRM_DISPLAY_HELPER
select DRM_KMS_HELPER
--
2.34.1

2024-04-22 11:50:26

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
> Hi all,
>
> As discussed on IRC with Maxime and Arnd, this series reverts the
> conversion of select to depends for various DRM helpers in series
> "[PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to
> depends on"[1], and various fixes for it. This conversion introduced a
> big usability issue when configuring a kernel and enabling DRM drivers
> that use DRM helper code: as drivers now depend on helpers, the user
> needs to know which helpers to enable, before the driver he is
> interested even becomes visible. The user should not need to know that,
> and drivers should select the helpers they need.
>
> Hence revert back to what we had before, where drivers selected the
> helpers (and any of their dependencies, if they can be met) they need.
> In general, when a symbol selects another symbol, it should just make
> sure the dependencies of the target symbol are met, which may mean
> adding dependencies to the source symbol.

I still disagree with this, because fundamentally the source symbol
really should not have to care about the dependencies of the target
symbol.

That said, I'm not going to keep arguing against this. Whatever.

BR,
Jani.

>
> Thanks for applying!
>
> [1] https://lore.kernel.org/r/[email protected]/
>
> Geert Uytterhoeven (11):
> Revert "drm: fix DRM_DISPLAY_DP_HELPER dependencies, part 2"
> Revert "drm/display: Select DRM_KMS_HELPER for DP helpers"
> Revert "drm/bridge: dw-hdmi: Make DRM_DW_HDMI selectable"
> Revert "drm: fix DRM_DISPLAY_DP_HELPER dependencies"
> Revert "drm: Switch DRM_DISPLAY_HDMI_HELPER to depends on"
> Revert "drm: Switch DRM_DISPLAY_HDCP_HELPER to depends on"
> Revert "drm: Switch DRM_DISPLAY_DP_HELPER to depends on"
> Revert "drm: Switch DRM_DISPLAY_DP_AUX_BUS to depends on"
> Revert "drm: Switch DRM_DISPLAY_HELPER to depends on"
> Revert "drm: Make drivers depends on DRM_DW_HDMI"
> Revert "drm/display: Make all helpers visible and switch to depends
> on"
>
> drivers/gpu/drm/Kconfig | 8 +++----
> drivers/gpu/drm/amd/amdgpu/Kconfig | 12 ++++------
> drivers/gpu/drm/bridge/Kconfig | 28 +++++++++++-----------
> drivers/gpu/drm/bridge/analogix/Kconfig | 18 +++++++-------
> drivers/gpu/drm/bridge/cadence/Kconfig | 8 +++----
> drivers/gpu/drm/bridge/imx/Kconfig | 4 ++--
> drivers/gpu/drm/bridge/synopsys/Kconfig | 6 ++---
> drivers/gpu/drm/display/Kconfig | 32 ++++++++++---------------
> drivers/gpu/drm/exynos/Kconfig | 4 ++--
> drivers/gpu/drm/i915/Kconfig | 8 +++----
> drivers/gpu/drm/imx/ipuv3/Kconfig | 5 ++--
> drivers/gpu/drm/ingenic/Kconfig | 2 +-
> drivers/gpu/drm/mediatek/Kconfig | 6 ++---
> drivers/gpu/drm/meson/Kconfig | 2 +-
> drivers/gpu/drm/msm/Kconfig | 8 +++----
> drivers/gpu/drm/nouveau/Kconfig | 10 ++++----
> drivers/gpu/drm/panel/Kconfig | 32 ++++++++++++-------------
> drivers/gpu/drm/radeon/Kconfig | 8 +++----
> drivers/gpu/drm/renesas/rcar-du/Kconfig | 2 +-
> drivers/gpu/drm/rockchip/Kconfig | 10 ++++----
> drivers/gpu/drm/sun4i/Kconfig | 2 +-
> drivers/gpu/drm/tegra/Kconfig | 8 +++----
> drivers/gpu/drm/vc4/Kconfig | 10 ++++----
> drivers/gpu/drm/xe/Kconfig | 13 ++++------
> drivers/gpu/drm/xlnx/Kconfig | 8 +++----
> 25 files changed, 116 insertions(+), 138 deletions(-)

--
Jani Nikula, Intel

2024-04-22 12:28:10

by Dmitry Baryshkov

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, Apr 22, 2024 at 02:50:09PM +0300, Jani Nikula wrote:
> On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
> > Hi all,
> >
> > As discussed on IRC with Maxime and Arnd, this series reverts the
> > conversion of select to depends for various DRM helpers in series
> > "[PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to
> > depends on"[1], and various fixes for it. This conversion introduced a
> > big usability issue when configuring a kernel and enabling DRM drivers
> > that use DRM helper code: as drivers now depend on helpers, the user
> > needs to know which helpers to enable, before the driver he is
> > interested even becomes visible. The user should not need to know that,
> > and drivers should select the helpers they need.
> >
> > Hence revert back to what we had before, where drivers selected the
> > helpers (and any of their dependencies, if they can be met) they need.
> > In general, when a symbol selects another symbol, it should just make
> > sure the dependencies of the target symbol are met, which may mean
> > adding dependencies to the source symbol.
>
> I still disagree with this, because fundamentally the source symbol
> really should not have to care about the dependencies of the target
> symbol.

I'd agree with you, but if the driver depends on helpers it becomes
ridiculous. So, it seems, we need a different solution for the original
problem.

> That said, I'm not going to keep arguing against this. Whatever.
>
>
> BR,
> Jani.
>
>
> >
> > Thanks for applying!
> >
> > [1] https://lore.kernel.org/r/[email protected]/
> >
> > Geert Uytterhoeven (11):
> > Revert "drm: fix DRM_DISPLAY_DP_HELPER dependencies, part 2"
> > Revert "drm/display: Select DRM_KMS_HELPER for DP helpers"
> > Revert "drm/bridge: dw-hdmi: Make DRM_DW_HDMI selectable"
> > Revert "drm: fix DRM_DISPLAY_DP_HELPER dependencies"
> > Revert "drm: Switch DRM_DISPLAY_HDMI_HELPER to depends on"
> > Revert "drm: Switch DRM_DISPLAY_HDCP_HELPER to depends on"
> > Revert "drm: Switch DRM_DISPLAY_DP_HELPER to depends on"
> > Revert "drm: Switch DRM_DISPLAY_DP_AUX_BUS to depends on"
> > Revert "drm: Switch DRM_DISPLAY_HELPER to depends on"
> > Revert "drm: Make drivers depends on DRM_DW_HDMI"
> > Revert "drm/display: Make all helpers visible and switch to depends
> > on"
> >
> > drivers/gpu/drm/Kconfig | 8 +++----
> > drivers/gpu/drm/amd/amdgpu/Kconfig | 12 ++++------
> > drivers/gpu/drm/bridge/Kconfig | 28 +++++++++++-----------
> > drivers/gpu/drm/bridge/analogix/Kconfig | 18 +++++++-------
> > drivers/gpu/drm/bridge/cadence/Kconfig | 8 +++----
> > drivers/gpu/drm/bridge/imx/Kconfig | 4 ++--
> > drivers/gpu/drm/bridge/synopsys/Kconfig | 6 ++---
> > drivers/gpu/drm/display/Kconfig | 32 ++++++++++---------------
> > drivers/gpu/drm/exynos/Kconfig | 4 ++--
> > drivers/gpu/drm/i915/Kconfig | 8 +++----
> > drivers/gpu/drm/imx/ipuv3/Kconfig | 5 ++--
> > drivers/gpu/drm/ingenic/Kconfig | 2 +-
> > drivers/gpu/drm/mediatek/Kconfig | 6 ++---
> > drivers/gpu/drm/meson/Kconfig | 2 +-
> > drivers/gpu/drm/msm/Kconfig | 8 +++----
> > drivers/gpu/drm/nouveau/Kconfig | 10 ++++----
> > drivers/gpu/drm/panel/Kconfig | 32 ++++++++++++-------------
> > drivers/gpu/drm/radeon/Kconfig | 8 +++----
> > drivers/gpu/drm/renesas/rcar-du/Kconfig | 2 +-
> > drivers/gpu/drm/rockchip/Kconfig | 10 ++++----
> > drivers/gpu/drm/sun4i/Kconfig | 2 +-
> > drivers/gpu/drm/tegra/Kconfig | 8 +++----
> > drivers/gpu/drm/vc4/Kconfig | 10 ++++----
> > drivers/gpu/drm/xe/Kconfig | 13 ++++------
> > drivers/gpu/drm/xlnx/Kconfig | 8 +++----
> > 25 files changed, 116 insertions(+), 138 deletions(-)
>
> --
> Jani Nikula, Intel

--
With best wishes
Dmitry

2024-04-22 12:30:49

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, Apr 22, 2024, at 13:50, Jani Nikula wrote:
> On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
>> Hi all,
>>
>> As discussed on IRC with Maxime and Arnd, this series reverts the
>> conversion of select to depends for various DRM helpers in series
>> "[PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to
>> depends on"[1], and various fixes for it. This conversion introduced a
>> big usability issue when configuring a kernel and enabling DRM drivers
>> that use DRM helper code: as drivers now depend on helpers, the user
>> needs to know which helpers to enable, before the driver he is
>> interested even becomes visible. The user should not need to know that,
>> and drivers should select the helpers they need.
>>
>> Hence revert back to what we had before, where drivers selected the
>> helpers (and any of their dependencies, if they can be met) they need.
>> In general, when a symbol selects another symbol, it should just make
>> sure the dependencies of the target symbol are met, which may mean
>> adding dependencies to the source symbol.

Thanks for doing this.

Acked-by: Arnd Bergmann <[email protected]>

> I still disagree with this, because fundamentally the source symbol
> really should not have to care about the dependencies of the target
> symbol.

Sorry you missed the IRC discussion on #armlinux, we should have
included you as well since you applied the original patch.

I think the reason for this revert is a bit more nuanced than
just the usability problem. Sorry if I'm dragging this out too
much, but I want to be sure that two points come across:

1. There is a semantic problem that is mostly subjective, but
with the naming as "helper", I generally expect it as a hidden
symbol that gets selected by its users, while calling same module
"feature" would be something that is user-enabled and that
other modules depend on. Both ways are commonly used in the
kernel and are not mistakes on their own.

2. Using "select" on user visible symbols that have dependencies
is a common source for bugs, and this is is a problem in
drivers/gpu/drm more than elsewhere in the kernel, as these
drivers traditionally select entire subsystems or drivers
(I2C, VIRTIO, INPUT, ACPI_WMI, BACKLIGHT_CLASS_DEVICE,
POWER_SUPPLY, SND_PCM, INTERCONNECT, ...). This regularly
leads to circular dependencies and we should fix all of them.
The display helpers however don't have this problem because
they do not have any dependencies outside of drivers/gpu/

Arnd

2024-04-22 13:28:59

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
> On Mon, Apr 22, 2024, at 13:50, Jani Nikula wrote:
>> On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
>>> Hi all,
>>>
>>> As discussed on IRC with Maxime and Arnd, this series reverts the
>>> conversion of select to depends for various DRM helpers in series
>>> "[PATCH v3 00/13] drm/display: Convert helpers Kconfig symbols to
>>> depends on"[1], and various fixes for it. This conversion introduced a
>>> big usability issue when configuring a kernel and enabling DRM drivers
>>> that use DRM helper code: as drivers now depend on helpers, the user
>>> needs to know which helpers to enable, before the driver he is
>>> interested even becomes visible. The user should not need to know that,
>>> and drivers should select the helpers they need.
>>>
>>> Hence revert back to what we had before, where drivers selected the
>>> helpers (and any of their dependencies, if they can be met) they need.
>>> In general, when a symbol selects another symbol, it should just make
>>> sure the dependencies of the target symbol are met, which may mean
>>> adding dependencies to the source symbol.
>
> Thanks for doing this.
>
> Acked-by: Arnd Bergmann <[email protected]>
>
>> I still disagree with this, because fundamentally the source symbol
>> really should not have to care about the dependencies of the target
>> symbol.
>
> Sorry you missed the IRC discussion on #armlinux, we should have
> included you as well since you applied the original patch.
>
> I think the reason for this revert is a bit more nuanced than
> just the usability problem. Sorry if I'm dragging this out too
> much, but I want to be sure that two points come across:
>
> 1. There is a semantic problem that is mostly subjective, but
> with the naming as "helper", I generally expect it as a hidden
> symbol that gets selected by its users, while calling same module
> "feature" would be something that is user-enabled and that
> other modules depend on. Both ways are commonly used in the
> kernel and are not mistakes on their own.

Fair enough. I believe for (optional) "feature" the common pattern would
then be depends on FEATURE || FEATURE=n.

> 2. Using "select" on user visible symbols that have dependencies
> is a common source for bugs, and this is is a problem in
> drivers/gpu/drm more than elsewhere in the kernel, as these
> drivers traditionally select entire subsystems or drivers
> (I2C, VIRTIO, INPUT, ACPI_WMI, BACKLIGHT_CLASS_DEVICE,
> POWER_SUPPLY, SND_PCM, INTERCONNECT, ...). This regularly
> leads to circular dependencies and we should fix all of them.

What annoys me is that the fixes tend to fall in two categories:

- Play catch with selecting the dependencies of the selected
symbols. "depends on" handles this recursively, while select does
not. There is no end to this, it just goes on and on, as the
dependencies of the selected symbols change over time. Often the
selects require unintuitive if patterns that are about the
implementation details of the symbol being selected.

- Brush the invalid configs under the rug by using IS_REACHABLE(),
switching from a loud link time failure to a silent runtime
failure. (I regularly reject patches adding IS_REACHABLE() to i915,
because from my pov e.g. i915=y backlight=m is an invalid
configuration that the user shouldn't have to debug at runtime. But I
can't express that in kconfig while everyone selects backlight.)

If you have other ideas how these should be fixed, I'm all ears.

> The display helpers however don't have this problem because
> they do not have any dependencies outside of drivers/gpu/

Fair enough, though I think they still suffer from some of them having
dependencies. (Wasn't this how the original patches and the debate all
got started?)

BR,
Jani.

--
Jani Nikula, Intel

2024-04-22 13:55:29

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, Apr 22, 2024, at 15:28, Jani Nikula wrote:
> On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
>> On Mon, Apr 22, 2024, at 13:50, Jani Nikula wrote:
>>
>>> I still disagree with this, because fundamentally the source symbol
>>> really should not have to care about the dependencies of the target
>>> symbol.
>>
>> Sorry you missed the IRC discussion on #armlinux, we should have
>> included you as well since you applied the original patch.
>>
>> I think the reason for this revert is a bit more nuanced than
>> just the usability problem. Sorry if I'm dragging this out too
>> much, but I want to be sure that two points come across:
>>
>> 1. There is a semantic problem that is mostly subjective, but
>> with the naming as "helper", I generally expect it as a hidden
>> symbol that gets selected by its users, while calling same module
>> "feature" would be something that is user-enabled and that
>> other modules depend on. Both ways are commonly used in the
>> kernel and are not mistakes on their own.
>
> Fair enough. I believe for (optional) "feature" the common pattern would
> then be depends on FEATURE || FEATURE=n.
>
>> 2. Using "select" on user visible symbols that have dependencies
>> is a common source for bugs, and this is is a problem in
>> drivers/gpu/drm more than elsewhere in the kernel, as these
>> drivers traditionally select entire subsystems or drivers
>> (I2C, VIRTIO, INPUT, ACPI_WMI, BACKLIGHT_CLASS_DEVICE,
>> POWER_SUPPLY, SND_PCM, INTERCONNECT, ...). This regularly
>> leads to circular dependencies and we should fix all of them.
>
> What annoys me is that the fixes tend to fall in two categories:
>
> - Play catch with selecting the dependencies of the selected
> symbols. "depends on" handles this recursively, while select does
> not.

I'm not sure where this misunderstanding comes from, as you
seem to be repeating the same incorrect assumption about
how select works that Maxime wrote in his changelog. To clarify,
this works exactly as one would expect:

config HELPER_A
tristate

config HELPER_B
tristate
select HELPER_A

config DRIVER
tristate "Turn on the driver and the helpers it uses"
select HELPER_B # this recursively selects HELPER_A

Whereas this one is broken:

config FEATURE_A
tristate "user visible if I2C is enabled"
depends on I2C

config HELPER_B
tristate # hidden
select FEATURE_A

config DRIVER
tristate "This driver is broken if I2C is disabled"
select HELPER_B

> There is no end to this, it just goes on and on, as the
> dependencies of the selected symbols change over time. Often the
> selects require unintuitive if patterns that are about the
> implementation details of the symbol being selected.

Agreed, that is the problem I frequently face with drivers/gpu/drm,
and most of the time it can only be solved by rewriting the whole
system to not select user-visible symbol at all.

Using 'depends on' by itself is unfortunately not enough to
avoid /all/ the problems. See e.g. today's failure

config DRM_DISPLAY_HELPER
tristate "DRM Display Helpers"
default y

config DRM_DISPLAY_DP_HELPER
bool "DRM DisplayPort Helpers"
depends on DRM_DISPLAY_HELPER

config DRM_PANEL_LG_SW43408
tristate "LG SW43408 panel"
depends on DRM_DISPLAY_DP_HELPER

This version is still broken for DRM_DISPLAY_HELPER=m,
DRM_DISPLAY_DP_HELPER=m, DRM_PANEL_LG_SW43408=y because
the dependency on the bool symbol is not enough to
ensure that DRM_DISPLAY_HELPER is also built-in, so you
still need explicit dependencies on both
DRM_DISPLAY_HELPER and DRM_DISPLAY_DP_HELPER in the users.

This can be solved by making DRM_DISPLAY_DP_HELPER a
tristate symbol and adjusting the #ifdef checks and
Makefile logic accordingly, which is exactly what you'd
need to do to make it work with 'select' as well.

> - Brush the invalid configs under the rug by using IS_REACHABLE(),
> switching from a loud link time failure to a silent runtime
> failure. (I regularly reject patches adding IS_REACHABLE() to i915,
> because from my pov e.g. i915=y backlight=m is an invalid
> configuration that the user shouldn't have to debug at runtime. But I
> can't express that in kconfig while everyone selects backlight.)

Thanks a lot for rejecting the IS_REACHABLE() patches, it is
indeed the worst way to handle those (I know, as I introduced
IS_REACHABLE() only to replace open-coded versions of the same,
not to have it as a feature or to use it in new code).

> If you have other ideas how these should be fixed, I'm all ears.
>
>> The display helpers however don't have this problem because
>> they do not have any dependencies outside of drivers/gpu/
>
> Fair enough, though I think they still suffer from some of them having
> dependencies. (Wasn't this how the original patches and the debate all
> got started?)

I believe that Maxime said on IRC that he only did the patches
originally because he expected problems with them based on his
understanding on how Kconfig works. I'm not aware of any
particular problem here.

Let me know if you see a problem with any of the symbols that
Geert has proposed for reverting, and I'll try to find a solution.
In my randconfig test environment, I have several patches that
I sent in the past to clean up the ACPI_VIDEO, I2C, BACKLIGHT and
LED dependencies to stop using 'select' as I could not otherwise
get nouveau, i915 and xe to build reliably, but that means I
may be missing some of the other problems.

Arnd

2024-04-22 17:02:33

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
> On Mon, Apr 22, 2024, at 15:28, Jani Nikula wrote:
>> On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
>>> On Mon, Apr 22, 2024, at 13:50, Jani Nikula wrote:
>>>
>>>> I still disagree with this, because fundamentally the source symbol
>>>> really should not have to care about the dependencies of the target
>>>> symbol.
>>>
>>> Sorry you missed the IRC discussion on #armlinux, we should have
>>> included you as well since you applied the original patch.
>>>
>>> I think the reason for this revert is a bit more nuanced than
>>> just the usability problem. Sorry if I'm dragging this out too
>>> much, but I want to be sure that two points come across:
>>>
>>> 1. There is a semantic problem that is mostly subjective, but
>>> with the naming as "helper", I generally expect it as a hidden
>>> symbol that gets selected by its users, while calling same module
>>> "feature" would be something that is user-enabled and that
>>> other modules depend on. Both ways are commonly used in the
>>> kernel and are not mistakes on their own.
>>
>> Fair enough. I believe for (optional) "feature" the common pattern would
>> then be depends on FEATURE || FEATURE=n.
>>
>>> 2. Using "select" on user visible symbols that have dependencies
>>> is a common source for bugs, and this is is a problem in
>>> drivers/gpu/drm more than elsewhere in the kernel, as these
>>> drivers traditionally select entire subsystems or drivers
>>> (I2C, VIRTIO, INPUT, ACPI_WMI, BACKLIGHT_CLASS_DEVICE,
>>> POWER_SUPPLY, SND_PCM, INTERCONNECT, ...). This regularly
>>> leads to circular dependencies and we should fix all of them.
>>
>> What annoys me is that the fixes tend to fall in two categories:
>>
>> - Play catch with selecting the dependencies of the selected
>> symbols. "depends on" handles this recursively, while select does
>> not.
>
> I'm not sure where this misunderstanding comes from, as you
> seem to be repeating the same incorrect assumption about
> how select works that Maxime wrote in his changelog. To clarify,
> this works exactly as one would expect:
>
> config HELPER_A
> tristate
>
> config HELPER_B
> tristate
> select HELPER_A
>
> config DRIVER
> tristate "Turn on the driver and the helpers it uses"
> select HELPER_B # this recursively selects HELPER_A
>
> Whereas this one is broken:
>
> config FEATURE_A
> tristate "user visible if I2C is enabled"
> depends on I2C
>
> config HELPER_B
> tristate # hidden
> select FEATURE_A
>
> config DRIVER
> tristate "This driver is broken if I2C is disabled"
> select HELPER_B

This case is really what I was referring to, although I was sloppy with
words there. I understand that select does work recursively for selects.

>> There is no end to this, it just goes on and on, as the
>> dependencies of the selected symbols change over time. Often the
>> selects require unintuitive if patterns that are about the
>> implementation details of the symbol being selected.
>
> Agreed, that is the problem I frequently face with drivers/gpu/drm,
> and most of the time it can only be solved by rewriting the whole
> system to not select user-visible symbol at all.
>
> Using 'depends on' by itself is unfortunately not enough to
> avoid /all/ the problems. See e.g. today's failure
>
> config DRM_DISPLAY_HELPER
> tristate "DRM Display Helpers"
> default y
>
> config DRM_DISPLAY_DP_HELPER
> bool "DRM DisplayPort Helpers"
> depends on DRM_DISPLAY_HELPER
>
> config DRM_PANEL_LG_SW43408
> tristate "LG SW43408 panel"
> depends on DRM_DISPLAY_DP_HELPER
>
> This version is still broken for DRM_DISPLAY_HELPER=m,
> DRM_DISPLAY_DP_HELPER=m, DRM_PANEL_LG_SW43408=y because
> the dependency on the bool symbol is not enough to
> ensure that DRM_DISPLAY_HELPER is also built-in, so you
> still need explicit dependencies on both
> DRM_DISPLAY_HELPER and DRM_DISPLAY_DP_HELPER in the users.
>
> This can be solved by making DRM_DISPLAY_DP_HELPER a
> tristate symbol and adjusting the #ifdef checks and
> Makefile logic accordingly, which is exactly what you'd
> need to do to make it work with 'select' as well.

So bool is kind of problematic for depends on and select even when it's
not really used for describing builtin vs. no, but rather yes vs. no?

>> - Brush the invalid configs under the rug by using IS_REACHABLE(),
>> switching from a loud link time failure to a silent runtime
>> failure. (I regularly reject patches adding IS_REACHABLE() to i915,
>> because from my pov e.g. i915=y backlight=m is an invalid
>> configuration that the user shouldn't have to debug at runtime. But I
>> can't express that in kconfig while everyone selects backlight.)
>
> Thanks a lot for rejecting the IS_REACHABLE() patches, it is
> indeed the worst way to handle those (I know, as I introduced
> IS_REACHABLE() only to replace open-coded versions of the same,
> not to have it as a feature or to use it in new code).
>
>> If you have other ideas how these should be fixed, I'm all ears.
>>
>>> The display helpers however don't have this problem because
>>> they do not have any dependencies outside of drivers/gpu/
>>
>> Fair enough, though I think they still suffer from some of them having
>> dependencies. (Wasn't this how the original patches and the debate all
>> got started?)
>
> I believe that Maxime said on IRC that he only did the patches
> originally because he expected problems with them based on his
> understanding on how Kconfig works. I'm not aware of any
> particular problem here.
>
> Let me know if you see a problem with any of the symbols that
> Geert has proposed for reverting, and I'll try to find a solution.

I think there will still be some things that select and some other
things that depends on DRM_DISPLAY_HELPER, for example. Usually that's a
recipe for kconfig failures down the line. (Is it ever a good idea?)

For example, after this series, we'll (again) have:

config DRM_DISPLAY_DP_AUX_CEC
bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
depends on DRM && DRM_DISPLAY_HELPER
select DRM_DISPLAY_DP_HELPER
select CEC_CORE

Should we now also drop the help from DRM_DISPLAY_HELPER, and select it
everywhere, including here, and in DRM_DISPLAY_HDCP_HELPER and
DRM_DISPLAY_HDMI_HELPER?

> In my randconfig test environment, I have several patches that
> I sent in the past to clean up the ACPI_VIDEO, I2C, BACKLIGHT and
> LED dependencies to stop using 'select' as I could not otherwise
> get nouveau, i915 and xe to build reliably, but that means I
> may be missing some of the other problems.

Yeah, these seem to be the really problematic ones. I admit I may have
been misguided in insisting the same approach to the helpers that should
be used here; at least the helpers should be easier to fix without
selecting the target symbol dependencies in the source symbols.

BR,
Jani.

--
Jani Nikula, Intel

2024-04-22 17:03:08

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

Hi Arnd,

CC kbuild

On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <[email protected]> wrote:
> On Mon, Apr 22, 2024, at 15:28, Jani Nikula wrote:
> > On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
> >> 2. Using "select" on user visible symbols that have dependencies
> >> is a common source for bugs, and this is is a problem in
> >> drivers/gpu/drm more than elsewhere in the kernel, as these
> >> drivers traditionally select entire subsystems or drivers
> >> (I2C, VIRTIO, INPUT, ACPI_WMI, BACKLIGHT_CLASS_DEVICE,
> >> POWER_SUPPLY, SND_PCM, INTERCONNECT, ...). This regularly
> >> leads to circular dependencies and we should fix all of them.
> >
> > What annoys me is that the fixes tend to fall in two categories:
> >
> > - Play catch with selecting the dependencies of the selected
> > symbols. "depends on" handles this recursively, while select does
> > not.
>
> I'm not sure where this misunderstanding comes from, as you
> seem to be repeating the same incorrect assumption about
> how select works that Maxime wrote in his changelog. To clarify,
> this works exactly as one would expect:
>
> config HELPER_A
> tristate
>
> config HELPER_B
> tristate
> select HELPER_A
>
> config DRIVER
> tristate "Turn on the driver and the helpers it uses"
> select HELPER_B # this recursively selects HELPER_A
>
> Whereas this one is broken:
>
> config FEATURE_A
> tristate "user visible if I2C is enabled"
> depends on I2C
>
> config HELPER_B
> tristate # hidden
> select FEATURE_A
>
> config DRIVER
> tristate "This driver is broken if I2C is disabled"
> select HELPER_B

So the DRIVER section should gain a "depends on I2C" statement.

Yamada-san: would it be difficult to modify Kconfig to ignore symbols
like DRIVER that select other symbols with unmet dependencies?
Currently it already warns about that.

Handling this implicitly (instead of the current explict "depends
on") would have the disadvantage though: a user who is not aware of
the implicit dependency may wonder why DRIVER is invisible in his
config interface.

>
> > There is no end to this, it just goes on and on, as the
> > dependencies of the selected symbols change over time. Often the
> > selects require unintuitive if patterns that are about the
> > implementation details of the symbol being selected.
>
> Agreed, that is the problem I frequently face with drivers/gpu/drm,
> and most of the time it can only be solved by rewriting the whole
> system to not select user-visible symbol at all.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

2024-04-22 17:15:10

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
> Hi Arnd,
>
> CC kbuild
>
> On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <[email protected]> wrote:
>> I'm not sure where this misunderstanding comes from, as you
>> seem to be repeating the same incorrect assumption about
>> how select works that Maxime wrote in his changelog. To clarify,
>> this works exactly as one would expect:
>>
>> config HELPER_A
>> tristate
>>
>> config HELPER_B
>> tristate
>> select HELPER_A
>>
>> config DRIVER
>> tristate "Turn on the driver and the helpers it uses"
>> select HELPER_B # this recursively selects HELPER_A
>>
>> Whereas this one is broken:
>>
>> config FEATURE_A
>> tristate "user visible if I2C is enabled"
>> depends on I2C
>>
>> config HELPER_B
>> tristate # hidden
>> select FEATURE_A
>>
>> config DRIVER
>> tristate "This driver is broken if I2C is disabled"
>> select HELPER_B
>
> So the DRIVER section should gain a "depends on I2C" statement.

Why should DRIVER have to care that HELPER_B needs either FEATURE_A or
I2C? It should only have to care about HELPER_B. And if the dependencies
of FEATURE_A or HELPER_B later change, that's their business, not
DRIVER's.

BR,
Jani.

>
> Yamada-san: would it be difficult to modify Kconfig to ignore symbols
> like DRIVER that select other symbols with unmet dependencies?
> Currently it already warns about that.
>
> Handling this implicitly (instead of the current explict "depends
> on") would have the disadvantage though: a user who is not aware of
> the implicit dependency may wonder why DRIVER is invisible in his
> config interface.

--
Jani Nikula, Intel

2024-04-22 18:02:38

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

Hi Jani,

On Mon, Apr 22, 2024 at 7:15 PM Jani Nikula <[email protected]> wrote:
> On Mon, 22 Apr 2024, Geert Uytterhoeven <[email protected]> wrote:
> > On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <[email protected]> wrote:
> >> I'm not sure where this misunderstanding comes from, as you
> >> seem to be repeating the same incorrect assumption about
> >> how select works that Maxime wrote in his changelog. To clarify,
> >> this works exactly as one would expect:
> >>
> >> config HELPER_A
> >> tristate
> >>
> >> config HELPER_B
> >> tristate
> >> select HELPER_A
> >>
> >> config DRIVER
> >> tristate "Turn on the driver and the helpers it uses"
> >> select HELPER_B # this recursively selects HELPER_A
> >>
> >> Whereas this one is broken:
> >>
> >> config FEATURE_A
> >> tristate "user visible if I2C is enabled"
> >> depends on I2C
> >>
> >> config HELPER_B
> >> tristate # hidden
> >> select FEATURE_A
> >>
> >> config DRIVER
> >> tristate "This driver is broken if I2C is disabled"
> >> select HELPER_B
> >
> > So the DRIVER section should gain a "depends on I2C" statement.
>
> Why should DRIVER have to care that HELPER_B needs either FEATURE_A or
> I2C? It should only have to care about HELPER_B. And if the dependencies
> of FEATURE_A or HELPER_B later change, that's their business, not
> DRIVER's.

That's correct. But currently the dependency on I2C is not handled
automatically.

> > Yamada-san: would it be difficult to modify Kconfig to ignore symbols
> > like DRIVER that select other symbols with unmet dependencies?
> > Currently it already warns about that.
> >
> > Handling this implicitly (instead of the current explict "depends
> > on") would have the disadvantage though: a user who is not aware of
> > the implicit dependency may wonder why DRIVER is invisible in his
> > config interface.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

2024-04-22 18:11:41

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

Hi Jani,

CC kbuild

On Mon, Apr 22, 2024 at 7:00 PM Jani Nikula <[email protected]> wrote:
> On Mon, 22 Apr 2024, "Arnd Bergmann" <[email protected]> wrote:
> > I'm not sure where this misunderstanding comes from, as you
> > seem to be repeating the same incorrect assumption about
> > how select works that Maxime wrote in his changelog. To clarify,
> > this works exactly as one would expect:
> >
> > config HELPER_A
> > tristate
> >
> > config HELPER_B
> > tristate
> > select HELPER_A
> >
> > config DRIVER
> > tristate "Turn on the driver and the helpers it uses"
> > select HELPER_B # this recursively selects HELPER_A
> >
> > Whereas this one is broken:
> >
> > config FEATURE_A
> > tristate "user visible if I2C is enabled"
> > depends on I2C
> >
> > config HELPER_B
> > tristate # hidden
> > select FEATURE_A
> >
> > config DRIVER
> > tristate "This driver is broken if I2C is disabled"
> > select HELPER_B
>
> This case is really what I was referring to, although I was sloppy with
> words there. I understand that select does work recursively for selects.
>
> >> There is no end to this, it just goes on and on, as the
> >> dependencies of the selected symbols change over time. Often the
> >> selects require unintuitive if patterns that are about the
> >> implementation details of the symbol being selected.
> >
> > Agreed, that is the problem I frequently face with drivers/gpu/drm,
> > and most of the time it can only be solved by rewriting the whole
> > system to not select user-visible symbol at all.
> >
> > Using 'depends on' by itself is unfortunately not enough to
> > avoid /all/ the problems. See e.g. today's failure
> >
> > config DRM_DISPLAY_HELPER
> > tristate "DRM Display Helpers"
> > default y
> >
> > config DRM_DISPLAY_DP_HELPER
> > bool "DRM DisplayPort Helpers"
> > depends on DRM_DISPLAY_HELPER
> >
> > config DRM_PANEL_LG_SW43408
> > tristate "LG SW43408 panel"
> > depends on DRM_DISPLAY_DP_HELPER
> >
> > This version is still broken for DRM_DISPLAY_HELPER=m,
> > DRM_DISPLAY_DP_HELPER=m, DRM_PANEL_LG_SW43408=y because
> > the dependency on the bool symbol is not enough to
> > ensure that DRM_DISPLAY_HELPER is also built-in, so you
> > still need explicit dependencies on both
> > DRM_DISPLAY_HELPER and DRM_DISPLAY_DP_HELPER in the users.
> >
> > This can be solved by making DRM_DISPLAY_DP_HELPER a
> > tristate symbol and adjusting the #ifdef checks and
> > Makefile logic accordingly, which is exactly what you'd
> > need to do to make it work with 'select' as well.
>
> So bool is kind of problematic for depends on and select even when it's
> not really used for describing builtin vs. no, but rather yes vs. no?

Yes, the underlying issue is that bool is used for two different things:
A. To enable a driver module that can be only built-in,
B. To enable an option or feature of a driver or subsystem.

Without this distinction, dependencies cannot be auto-propagated 100%
correctly. Fixing that would require introducing a third type (and possibly
renaming the existing ones to end up with 3 good names).

Actually two types could work:
1. driver,
2. option,
as case A is just a driver that can only be built-in (i.e. "depends on y",
which is similar to the behavior with CONFIG_MODULES=n).

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

2024-04-22 18:24:24

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Mon, Apr 22, 2024, at 18:58, Geert Uytterhoeven wrote:
> On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <[email protected]> wrote:
>> On Mon, Apr 22, 2024, at 15:28, Jani Nikula wrote:
>> Whereas this one is broken:
>>
>> config FEATURE_A
>> tristate "user visible if I2C is enabled"
>> depends on I2C
>>
>> config HELPER_B
>> tristate # hidden
>> select FEATURE_A
>>
>> config DRIVER
>> tristate "This driver is broken if I2C is disabled"
>> select HELPER_B
>
> So the DRIVER section should gain a "depends on I2C" statement.

That is of course the common workaround, but my point was
that nothing should ever 'select I2C' or any of the other
subsystems that are user visible.

> Yamada-san: would it be difficult to modify Kconfig to ignore symbols
> like DRIVER that select other symbols with unmet dependencies?
> Currently it already warns about that.
>
> Handling this implicitly (instead of the current explict "depends
> on") would have the disadvantage though: a user who is not aware of
> the implicit dependency may wonder why DRIVER is invisible in his
> config interface.

I think hiding this would make it much harder to get anything
right. The symbols in question are almost all ones that should
be enabled in normal configs, and the 'make menuconfig' help
doesn't make it too hard to figure things out normally, we just
have to find a way to avoid regressions when converting things
to 'depends on' that used an incorrect 'select'.

Arnd

2024-04-22 19:43:00

by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH 00/11] drm: Restore helper usability

On Tue, Apr 23, 2024 at 3:24 AM Arnd Bergmann <[email protected]> wrote:
>
> On Mon, Apr 22, 2024, at 18:58, Geert Uytterhoeven wrote:
> > On Mon, Apr 22, 2024 at 3:55 PM Arnd Bergmann <[email protected]> wrote:
> >> On Mon, Apr 22, 2024, at 15:28, Jani Nikula wrote:
> >> Whereas this one is broken:
> >>
> >> config FEATURE_A
> >> tristate "user visible if I2C is enabled"
> >> depends on I2C
> >>
> >> config HELPER_B
> >> tristate # hidden
> >> select FEATURE_A
> >>
> >> config DRIVER
> >> tristate "This driver is broken if I2C is disabled"
> >> select HELPER_B
> >
> > So the DRIVER section should gain a "depends on I2C" statement.
>
> That is of course the common workaround, but my point was
> that nothing should ever 'select I2C' or any of the other
> subsystems that are user visible.
>
> > Yamada-san: would it be difficult to modify Kconfig to ignore symbols
> > like DRIVER that select other symbols with unmet dependencies?
> > Currently it already warns about that.
> >
> > Handling this implicitly (instead of the current explict "depends
> > on") would have the disadvantage though: a user who is not aware of
> > the implicit dependency may wonder why DRIVER is invisible in his
> > config interface.
>
> I think hiding this would make it much harder to get anything
> right. The symbols in question are almost all ones that should
> be enabled in normal configs, and the 'make menuconfig' help
> doesn't make it too hard to figure things out normally, we just
> have to find a way to avoid regressions when converting things
> to 'depends on' that used an incorrect 'select'.
>
> Arnd

I am confused because you repeatedly discussed
the missing I2C dependency.

Are you talking about DRM drivers,
or is it just "an example" in general?

DRM selects I2C.

https://github.com/torvalds/linux/blob/v6.9-rc4/drivers/gpu/drm/Kconfig#L16

If you make sure individual DRM drivers depend on DRM,
none of them can be enabled without I2C.

Currently, this is not guaranteed just because
DRM folks do not know how to use the "menuconfig" syntax.

The "menuconfig" makes sense only when it is
followed by "if".

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 5a0c476361c3..6984b3fea271 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -29,6 +29,8 @@ menuconfig DRM
details. You should also select and configure AGP
(/dev/agpgart) support if it is available for your platform.

+if DRM
+
config DRM_MIPI_DBI
tristate
depends on DRM
@@ -414,3 +416,5 @@ config DRM_LIB_RANDOM
config DRM_PRIVACY_SCREEN
bool
default n
+
+endif

--
Best Regards
Masahiro Yamada

2024-04-22 20:47:07