LinuxLists.cc - [PATCH v3 00/25] Unify PCI error response checking

2021-10-21 15:11:03

Subject: [PATCH v3 00/25] Unify PCI error response checking

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

This patch series adds PCI_ERROR_RESPONSE definition and other helper
definition SET_PCI_ERROR_RESPONSE and RESPONSE_IS_PCI_ERROR and uses it
where appropriate to make these checks consistent and easier to find.

This helps unify PCI error response checking and make error check
consistent and easier to find.

This series also ensures that the error response fabrication now happens
in the PCI_OP_READ and PCI_USER_READ_CONFIG. This removes the
responsibility from controller drivers to do the error response setting.

Patch 1:
- Adds the PCI_ERROR_RESPONSE and other related defintions
- All other patches are dependent on this patch. This patch needs to
be applied first, before the others

Patch 2:
- Error fabrication happens in PCI_OP_READ and PCI_USER_READ_CONFIG
whenever the data read via the controller driver fails.
- This patch needs to be applied before, Patch 4/24 to Patch 15/24 are
applied.

Patch 3:
- Uses SET_PCI_ERROR_RESPONSE() when device is not found

Patch 4 - 15:
- Removes redundant error fabrication that happens in controller
drivers when the read from a PCI device fails.
- These patches are dependent on Patch 2/24 of the series.
- These can be applied in any order.

Patch 16 - 22:
- Uses RESPONSE_IS_PCI_ERROR() to check the reads from hardware
- Patches can be applied in any order.

Patch 23 - 25:
- Edits the comments to include PCI_ERROR_RESPONSE alsong with
0xFFFFFFFF, so that it becomes easier to grep for faulty
hardware reads.

Changelog
=========
v3:
- Change RESPONSE_IS_PCI_ERROR macro definition
- Fix the macros, Add () around macro parameters
- Fix alignment issue in Patch 2/24
- Add proper receipients for all the patches

v2:
- Instead of using SET_PCI_ERROR_RESPONSE in all controller drivers
to fabricate error response, only use them in PCI_OP_READ and
PCI_USER_READ_CONFIG

Naveen Naidu (25):
[Patch 1/25] PCI: Add PCI_ERROR_RESPONSE and it's related definitions
[Patch 2/25] PCI: Set error response in config access defines when ops->read() fails
[Patch 3/25] PCI: Use SET_PCI_ERROR_RESPONSE() when device not found
[Patch 4/25] PCI: Remove redundant error fabrication when device read fails
[Patch 5/25] PCI: thunder: Remove redundant error fabrication when device read fails
[Patch 6/25] PCI: iproc: Remove redundant error fabrication when device read fails
[Patch 7/25] PCI: mediatek: Remove redundant error fabrication when device read fails
[Patch 8/25] PCI: exynos: Remove redundant error fabrication when device read fails
[Patch 9/25] PCI: histb: Remove redundant error fabrication when device read fails
[Patch 10/25] PCI: kirin: Remove redundant error fabrication when device read fails
[Patch 11/25] PCI: aardvark: Remove redundant error fabrication when device read fails
[Patch 12/25] PCI: mvebu: Remove redundant error fabrication when device read fails
[Patch 13/25] PCI: altera: Remove redundant error fabrication when device read fails
[Patch 14/25] PCI: rcar: Remove redundant error fabrication when device read fails
[Patch 15/25] PCI: rockchip: Remove redundant error fabrication when device read fails
[Patch 16/25] PCI/ERR: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 17/25] PCI: vmd: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 18/25] PCI: pciehp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 19/25] PCI/DPC: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 20/25] PCI/PME: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 21/25] PCI: cpqphp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
[Patch 22/25] PCI: Use PCI_ERROR_RESPONSE to specify hardware error
[Patch 23/25] PCI: keystone: Use PCI_ERROR_RESPONSE to specify hardware error
[Patch 24/25] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error
[Patch 25/25] PCI: xgene: Use PCI_ERROR_RESPONSE to specify hardware error

drivers/pci/access.c | 32 +++++++-------
drivers/pci/controller/dwc/pci-exynos.c | 4 +-
drivers/pci/controller/dwc/pci-keystone.c | 4 +-
drivers/pci/controller/dwc/pcie-histb.c | 4 +-
drivers/pci/controller/dwc/pcie-kirin.c | 4 +-
drivers/pci/controller/pci-aardvark.c | 10 +----
drivers/pci/controller/pci-hyperv.c | 2 +-
drivers/pci/controller/pci-mvebu.c | 8 +---
drivers/pci/controller/pci-thunder-ecam.c | 46 +++++++--------------
drivers/pci/controller/pci-thunder-pem.c | 4 +-
drivers/pci/controller/pci-xgene.c | 8 ++--
drivers/pci/controller/pcie-altera.c | 4 +-
drivers/pci/controller/pcie-iproc.c | 4 +-
drivers/pci/controller/pcie-mediatek.c | 11 +----
drivers/pci/controller/pcie-rcar-host.c | 4 +-
drivers/pci/controller/pcie-rockchip-host.c | 4 +-
drivers/pci/controller/vmd.c | 2 +-
drivers/pci/hotplug/cpqphp_ctrl.c | 4 +-
drivers/pci/hotplug/pciehp_hpc.c | 10 ++---
drivers/pci/pci.c | 10 ++---
drivers/pci/pcie/dpc.c | 4 +-
drivers/pci/pcie/pme.c | 4 +-
drivers/pci/probe.c | 10 ++---
include/linux/pci.h | 9 ++++
24 files changed, 85 insertions(+), 121 deletions(-)

--
2.25.1

2021-10-21 15:12:10

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 02/25] PCI: Set error response in config access defines when ops->read() fails

Make PCI_OP_READ and PCI_USER_READ_CONFIG set the data value with error
response (~0), when the PCI device read by a host controller fails.

This ensures that the controller drivers no longer need to fabricate
(~0) value when they detect error. It also gurantees that the error
response (~0) is always set when the controller drivers fails to read a
config register from a device.

This makes error response fabrication consistent and helps in removal of
a lot of repeated code.

Suggested-by: Rob Herring <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/access.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 46935695cfb9..0f732ba2f71a 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -42,7 +42,10 @@ int noinline pci_bus_read_config_##size \
if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
pci_lock_config(flags); \
res = bus->ops->read(bus, devfn, pos, len, &data); \
- *value = (type)data; \
+ if (res) \
+ SET_PCI_ERROR_RESPONSE(value); \
+ else \
+ *value = (type)data; \
pci_unlock_config(flags); \
return res; \
}
@@ -228,7 +231,10 @@ int pci_user_read_config_##size \
ret = dev->bus->ops->read(dev->bus, dev->devfn, \
pos, sizeof(type), &data); \
raw_spin_unlock_irq(&pci_lock); \
- *val = (type)data; \
+ if (ret) \
+ SET_PCI_ERROR_RESPONSE(val); \
+ else \
+ *val = (type)data; \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
--
2.25.1

2021-10-21 15:12:13

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 03/25] PCI: Use SET_PCI_ERROR_RESPONSE() when device not found

2021-10-21 15:12:24

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 05/25] PCI: thunder: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pci-thunder-ecam.c | 46 ++++++++---------------
drivers/pci/controller/pci-thunder-pem.c | 4 +-
2 files changed, 17 insertions(+), 33 deletions(-)

diff --git a/drivers/pci/controller/pci-thunder-ecam.c b/drivers/pci/controller/pci-thunder-ecam.c
index ffd84656544f..a95bb58afd52 100644
--- a/drivers/pci/controller/pci-thunder-ecam.c
+++ b/drivers/pci/controller/pci-thunder-ecam.c
@@ -41,10 +41,9 @@ static int handle_ea_bar(u32 e0, int bar, struct pci_bus *bus,
}
if (where_a == 0x4) {
addr = bus->ops->map_bus(bus, devfn, bar); /* BAR 0 */
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
v = readl(addr);
v &= ~0xf;
v |= 2; /* EA entry-1. Base-L */
@@ -56,10 +55,9 @@ static int handle_ea_bar(u32 e0, int bar, struct pci_bus *bus,
u32 barl_rb;

addr = bus->ops->map_bus(bus, devfn, bar); /* BAR 0 */
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
barl_orig = readl(addr + 0);
writel(0xffffffff, addr + 0);
barl_rb = readl(addr + 0);
@@ -72,10 +70,9 @@ static int handle_ea_bar(u32 e0, int bar, struct pci_bus *bus,
}
if (where_a == 0xc) {
addr = bus->ops->map_bus(bus, devfn, bar + 4); /* BAR 1 */
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
v = readl(addr); /* EA entry-3. Base-H */
set_val(v, where, size, val);
return PCIBIOS_SUCCESSFUL;
@@ -104,10 +101,8 @@ static int thunder_ecam_p2_config_read(struct pci_bus *bus, unsigned int devfn,
}

addr = bus->ops->map_bus(bus, devfn, where_a);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

v = readl(addr);

@@ -135,10 +130,8 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
int where_a = where & ~3;

addr = bus->ops->map_bus(bus, devfn, 0xc);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

v = readl(addr);

@@ -146,10 +139,8 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
cfg_type = (v >> 16) & 0x7f;

addr = bus->ops->map_bus(bus, devfn, 8);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

class_rev = readl(addr);
if (class_rev == 0xffffffff)
@@ -176,10 +167,8 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
}

addr = bus->ops->map_bus(bus, devfn, 0);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

vendor_device = readl(addr);
if (vendor_device == 0xffffffff)
@@ -196,10 +185,9 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
bool is_tns = (vendor_device == 0xa01f177d);

addr = bus->ops->map_bus(bus, devfn, 0x70);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
/* E_CAP */
v = readl(addr);
has_msix = (v & 0xff00) != 0;
@@ -211,10 +199,9 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
}
if (where_a == 0xb0) {
addr = bus->ops->map_bus(bus, devfn, where_a);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
v = readl(addr);
if (v & 0xff00)
pr_err("Bad MSIX cap header: %08x\n", v);
@@ -268,10 +255,9 @@ static int thunder_ecam_config_read(struct pci_bus *bus, unsigned int devfn,

if (where_a == 0x70) {
addr = bus->ops->map_bus(bus, devfn, where_a);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
+
v = readl(addr);
if (v & 0xff00)
pr_err("Bad PCIe cap header: %08x\n", v);
diff --git a/drivers/pci/controller/pci-thunder-pem.c b/drivers/pci/controller/pci-thunder-pem.c
index 0660b9da204f..06a9855cb431 100644
--- a/drivers/pci/controller/pci-thunder-pem.c
+++ b/drivers/pci/controller/pci-thunder-pem.c
@@ -41,10 +41,8 @@ static int thunder_pem_bridge_read(struct pci_bus *bus, unsigned int devfn,
struct pci_config_window *cfg = bus->sysdata;
struct thunder_pem_pci *pem_pci = (struct thunder_pem_pci *)cfg->priv;

- if (devfn != 0 || where >= 2048) {
- *val = ~0;
+ if (devfn != 0 || where >= 2048)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

/*
* 32-bit accesses only. Write the address to the low order
--
2.25.1

2021-10-21 15:12:30

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 04/25] PCI: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/access.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index a6bcbad04d89..2705a4412e69 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -83,10 +83,8 @@ int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
void __iomem *addr;

addr = bus->ops->map_bus(bus, devfn, where);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

if (size == 1)
*val = readb(addr);
@@ -125,10 +123,8 @@ int pci_generic_config_read32(struct pci_bus *bus, unsigned int devfn,
void __iomem *addr;

addr = bus->ops->map_bus(bus, devfn, where & ~0x3);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

*val = readl(addr);

--
2.25.1

2021-10-21 15:12:38

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 06/25] PCI: iproc: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pcie-iproc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
index 30ac5fbefbbf..e3d86416a4fb 100644
--- a/drivers/pci/controller/pcie-iproc.c
+++ b/drivers/pci/controller/pcie-iproc.c
@@ -659,10 +659,8 @@ static int iproc_pci_raw_config_read32(struct iproc_pcie *pcie,
void __iomem *addr;

addr = iproc_pcie_map_cfg_bus(pcie, 0, devfn, where & ~0x3);
- if (!addr) {
- *val = ~0;
+ if (!addr)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

*val = readl(addr);

--
2.25.1

2021-10-21 15:12:53

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 07/25] PCI: mediatek: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pcie-mediatek.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
index 2f3f974977a3..a19f8ec5d392 100644
--- a/drivers/pci/controller/pcie-mediatek.c
+++ b/drivers/pci/controller/pcie-mediatek.c
@@ -365,19 +365,12 @@ static int mtk_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
{
struct mtk_pcie_port *port;
u32 bn = bus->number;
- int ret;

port = mtk_pcie_find_port(bus, devfn);
- if (!port) {
- *val = ~0;
+ if (!port)
return PCIBIOS_DEVICE_NOT_FOUND;
- }
-
- ret = mtk_pcie_hw_rd_cfg(port, bn, devfn, where, size, val);
- if (ret)
- *val = ~0;

- return ret;
+ return mtk_pcie_hw_rd_cfg(port, bn, devfn, where, size, val);
}

static int mtk_pcie_config_write(struct pci_bus *bus, unsigned int devfn,
--
2.25.1

2021-10-21 15:13:06

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 08/25] PCI: exynos: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/dwc/pci-exynos.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-exynos.c b/drivers/pci/controller/dwc/pci-exynos.c
index c24dab383654..f9526d6de160 100644
--- a/drivers/pci/controller/dwc/pci-exynos.c
+++ b/drivers/pci/controller/dwc/pci-exynos.c
@@ -216,10 +216,8 @@ static int exynos_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn,
{
struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata);

- if (PCI_SLOT(devfn)) {
- *val = ~0;
+ if (PCI_SLOT(devfn))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

*val = dw_pcie_read_dbi(pci, where, size);
return PCIBIOS_SUCCESSFUL;
--
2.25.1

2021-10-21 15:13:31

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 10/25] PCI: kirin: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/dwc/pcie-kirin.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
index 026fd1e42a55..56ccc5ceee50 100644
--- a/drivers/pci/controller/dwc/pcie-kirin.c
+++ b/drivers/pci/controller/dwc/pcie-kirin.c
@@ -330,10 +330,8 @@ static int kirin_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn,
{
struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata);

- if (PCI_SLOT(devfn)) {
- *val = ~0;
+ if (PCI_SLOT(devfn))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

*val = dw_pcie_read_dbi(pci, where, size);
return PCIBIOS_SUCCESSFUL;
--
2.25.1

2021-10-21 15:13:35

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 09/25] PCI: histb: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/dwc/pcie-histb.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-histb.c b/drivers/pci/controller/dwc/pcie-histb.c
index 86f9d16c50d7..410555dccb6d 100644
--- a/drivers/pci/controller/dwc/pcie-histb.c
+++ b/drivers/pci/controller/dwc/pcie-histb.c
@@ -127,10 +127,8 @@ static int histb_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn,
{
struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata);

- if (PCI_SLOT(devfn)) {
- *val = ~0;
+ if (PCI_SLOT(devfn))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

*val = dw_pcie_read_dbi(pci, where, size);
return PCIBIOS_SUCCESSFUL;
--
2.25.1

2021-10-21 15:14:56

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 11/25] PCI: aardvark: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pci-aardvark.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 596ebcfcc82d..1af772c76d06 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -893,10 +893,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
u32 reg;
int ret;

- if (!advk_pcie_valid_device(pcie, bus, devfn)) {
- *val = 0xffffffff;
+ if (!advk_pcie_valid_device(pcie, bus, devfn))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

if (pci_is_root_bus(bus))
return pci_bridge_emul_conf_read(&pcie->bridge, where,
@@ -920,7 +918,6 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
*val = CFG_RD_CRS_VAL;
return PCIBIOS_SUCCESSFUL;
}
- *val = 0xffffffff;
return PCIBIOS_SET_FAILED;
}

@@ -955,16 +952,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
*val = CFG_RD_CRS_VAL;
return PCIBIOS_SUCCESSFUL;
}
- *val = 0xffffffff;
return PCIBIOS_SET_FAILED;
}

/* Check PIO status and get the read result */
ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
- if (ret < 0) {
- *val = 0xffffffff;
+ if (ret < 0)
return PCIBIOS_SET_FAILED;
- }

if (size == 1)
*val = (*val >> (8 * (where & 3))) & 0xff;
--
2.25.1

2021-10-21 15:15:52

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 12/25] PCI: mvebu: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pci-mvebu.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index ed13e81cd691..70a96af8cd2f 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -653,20 +653,16 @@ static int mvebu_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where,
int ret;

port = mvebu_pcie_find_port(pcie, bus, devfn);
- if (!port) {
- *val = 0xffffffff;
+ if (!port)
return PCIBIOS_DEVICE_NOT_FOUND;
- }

/* Access the emulated PCI-to-PCI bridge */
if (bus->number == 0)
return pci_bridge_emul_conf_read(&port->bridge, where,
size, val);

- if (!mvebu_pcie_link_up(port)) {
- *val = 0xffffffff;
+ if (!mvebu_pcie_link_up(port))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

/* Access the real PCIe interface */
ret = mvebu_pcie_hw_rd_conf(port, bus, devfn,
--
2.25.1

2021-10-21 15:15:55

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 16/25] PCI/ERR: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

Use RESPONSE_IS_PCI_ERROR() to check the response we get when we read
data from hardware.

This unifies PCI error response checking and make error checks
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/pci.c | 10 +++++-----
drivers/pci/probe.c | 10 +++++-----
2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ce2ab62b64cf..4eaf29f004bd 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1077,7 +1077,7 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
return -EIO;

pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
- if (pmcsr == (u16) ~0) {
+ if (RESPONSE_IS_PCI_ERROR(pmcsr)) {
pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n",
pci_power_name(dev->current_state),
pci_power_name(state));
@@ -1239,16 +1239,16 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
* After reset, the device should not silently discard config
* requests, but it may still indicate that it needs more time by
* responding to them with CRS completions. The Root Port will
- * generally synthesize ~0 data to complete the read (except when
- * CRS SV is enabled and the read was for the Vendor ID; in that
- * case it synthesizes 0x0001 data).
+ * generally synthesize ~0 (PCI_ERROR_RESPONSE) data to complete
+ * the read (except when CRS SV is enabled and the read was for the
+ * Vendor ID; in that case it synthesizes 0x0001 data).
*
* Wait for the device to return a non-CRS completion. Read the
* Command register instead of Vendor ID so we don't have to
* contend with the CRS SV value.
*/
pci_read_config_dword(dev, PCI_COMMAND, &id);
- while (id == ~0) {
+ while (RESPONSE_IS_PCI_ERROR(id)) {
if (delay > timeout) {
pci_warn(dev, "not ready %dms after %s; giving up\n",
delay - 1, reset_type);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index d9fc02a71baa..8bf4034ddbd4 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -206,14 +206,14 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
* memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
* 1 must be clear.
*/
- if (sz == 0xffffffff)
+ if (RESPONSE_IS_PCI_ERROR(sz))
sz = 0;

/*
* I don't know how l can have all bits set. Copied from old code.
* Maybe it fixes a bug on some ancient platform.
*/
- if (l == 0xffffffff)
+ if (RESPONSE_IS_PCI_ERROR(l))
l = 0;

if (type == pci_bar_unknown) {
@@ -1660,7 +1660,7 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)

if (pci_read_config_dword(dev, pos, &status) != PCIBIOS_SUCCESSFUL)
return PCI_CFG_SPACE_SIZE;
- if (status == 0xffffffff || pci_ext_cfg_is_aliased(dev))
+ if (RESPONSE_IS_PCI_ERROR(status) || pci_ext_cfg_is_aliased(dev))
return PCI_CFG_SPACE_SIZE;

return PCI_CFG_SPACE_EXP_SIZE;
@@ -2336,8 +2336,8 @@ bool pci_bus_generic_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
return false;

- /* Some broken boards return 0 or ~0 if a slot is empty: */
- if (*l == 0xffffffff || *l == 0x00000000 ||
+ /* Some broken boards return 0 or ~0 (PCI_ERROR_RESPONSE) if a slot is empty: */
+ if (RESPONSE_IS_PCI_ERROR(*l) || *l == 0x00000000 ||
*l == 0x0000ffff || *l == 0xffff0000)
return false;

--
2.25.1

2021-10-21 15:15:58

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 13/25] PCI: altera: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pcie-altera.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-altera.c b/drivers/pci/controller/pcie-altera.c
index 2513e9363236..a6bdf9aff833 100644
--- a/drivers/pci/controller/pcie-altera.c
+++ b/drivers/pci/controller/pcie-altera.c
@@ -510,10 +510,8 @@ static int altera_pcie_cfg_read(struct pci_bus *bus, unsigned int devfn,
if (altera_pcie_hide_rc_bar(bus, devfn, where))
return PCIBIOS_BAD_REGISTER_NUMBER;

- if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) {
- *value = 0xffffffff;
+ if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn)))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

return _altera_pcie_cfg_read(pcie, bus->number, devfn, where, size,
value);
--
2.25.1

2021-10-21 15:16:04

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 17/25] PCI: vmd: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:16:14

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 14/25] PCI: rcar: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Reviewed-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pcie-rcar-host.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c
index 8f3131844e77..1324cb984ed5 100644
--- a/drivers/pci/controller/pcie-rcar-host.c
+++ b/drivers/pci/controller/pcie-rcar-host.c
@@ -161,10 +161,8 @@ static int rcar_pcie_read_conf(struct pci_bus *bus, unsigned int devfn,

ret = rcar_pcie_config_access(host, RCAR_PCI_ACCESS_READ,
bus, devfn, where, val);
- if (ret != PCIBIOS_SUCCESSFUL) {
- *val = 0xffffffff;
+ if (ret != PCIBIOS_SUCCESSFUL)
return ret;
- }

if (size == 1)
*val = (*val >> (BITS_PER_BYTE * (where & 3))) & 0xff;
--
2.25.1

2021-10-21 15:16:26

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 20/25] PCI/PME: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:16:36

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 15/25] PCI: rockchip: Remove redundant error fabrication when device read fails

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pcie-rockchip-host.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index c52316d0bfd2..45a28880f322 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -221,10 +221,8 @@ static int rockchip_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where,
{
struct rockchip_pcie *rockchip = bus->sysdata;

- if (!rockchip_pcie_valid_device(rockchip, bus, PCI_SLOT(devfn))) {
- *val = 0xffffffff;
+ if (!rockchip_pcie_valid_device(rockchip, bus, PCI_SLOT(devfn)))
return PCIBIOS_DEVICE_NOT_FOUND;
- }

if (pci_is_root_bus(bus))
return rockchip_pcie_rd_own_conf(rockchip, where, size, val);
--
2.25.1

2021-10-21 15:16:37

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 21/25] PCI: cpqphp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:16:37

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 22/25] PCI: Use PCI_ERROR_RESPONSE to specify hardware error

Include PCI_ERROR_RESPONSE along with 0xFFFF and 0xFFFFFFFF in the
comment to specify a hardware error. This makes MMIO read errors
easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/access.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 2705a4412e69..baff68916f17 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -413,8 +413,8 @@ int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val)
ret = pci_read_config_word(dev, pci_pcie_cap(dev) + pos, val);
/*
* Reset *val to 0 if pci_read_config_word() fails, it may
- * have been written as 0xFFFF if hardware error happens
- * during pci_read_config_word().
+ * have been written as 0xFFFF (PCI_ERROR_RESPONSE) if hardware error
+ * happens during pci_read_config_word().
*/
if (ret)
*val = 0;
@@ -448,8 +448,8 @@ int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val)
ret = pci_read_config_dword(dev, pci_pcie_cap(dev) + pos, val);
/*
* Reset *val to 0 if pci_read_config_dword() fails, it may
- * have been written as 0xFFFFFFFF if hardware error happens
- * during pci_read_config_dword().
+ * have been written as 0xFFFFFFFF (PCI_ERROR_RESPONSE) if hardware
+ * error happens during pci_read_config_dword().
*/
if (ret)
*val = 0;
--
2.25.1

2021-10-21 15:16:54

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 24/25] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error

Include PCI_ERROR_RESPONSE along with 0xFFFFFFFF in the comment to
specify a hardware error. This makes MMIO read errors easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pci-hyperv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 67c46e52c0dc..7e1102e3d7c6 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1774,7 +1774,7 @@ static void prepopulate_bars(struct hv_pcibus_device *hbus)
* If the memory enable bit is already set, Hyper-V silently ignores
* the below BAR updates, and the related PCI device driver can not
* work, because reading from the device register(s) always returns
- * 0xFFFFFFFF.
+ * 0xFFFFFFFF (PCI_ERROR_RESPONSE).
*/
list_for_each_entry(hpdev, &hbus->children, list_entry) {
_hv_pcifront_read_config(hpdev, PCI_COMMAND, 2, &command);
--
2.25.1

2021-10-21 15:16:58

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 25/25] PCI: xgene: Use PCI_ERROR_RESPONSE to specify hardware error

Include PCI_ERROR_RESPONSE along with 0xffffffff in the comment to
specify a hardware error. This makes MMIO read errors easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/pci-xgene.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/pci-xgene.c b/drivers/pci/controller/pci-xgene.c
index e64536047b65..4b10794e1ba1 100644
--- a/drivers/pci/controller/pci-xgene.c
+++ b/drivers/pci/controller/pci-xgene.c
@@ -176,10 +176,10 @@ static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
* Retry Status (CRS) logic: when CRS Software Visibility is
* enabled and we read the Vendor and Device ID of a non-existent
* device, the controller fabricates return data of 0xFFFF0001
- * ("device exists but is not ready") instead of 0xFFFFFFFF
- * ("device does not exist"). This causes the PCI core to retry
- * the read until it times out. Avoid this by not claiming to
- * support CRS SV.
+ * ("device exists but is not ready") instead of
+ * 0xFFFFFFFF (PCI_ERROR_RESPONSE) ("device does not exist"). This causes
+ * the PCI core to retry the read until it times out.
+ * Avoid this by not claiming to support CRS SV.
*/
if (pci_is_root_bus(bus) && (port->version == XGENE_PCIE_IP_VER_1) &&
((where & ~0x3) == XGENE_V1_PCI_EXP_CAP + PCI_EXP_RTCTL))
--
2.25.1

2021-10-21 15:17:25

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 18/25] PCI: pciehp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:17:27

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 19/25] PCI/DPC: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:17:28

by Naveen Naidu

[permalink] [raw]

Subject: [PATCH v3 23/25] PCI: keystone: Use PCI_ERROR_RESPONSE to specify hardware error

Include PCI_ERROR_RESPONSE along with 0xffffffff in the comment to
specify a hardware error. This makes MMIO read errors easier to find.

Signed-off-by: Naveen Naidu <[email protected]>
---
drivers/pci/controller/dwc/pci-keystone.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 865258d8c53c..25b11610b500 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -748,8 +748,8 @@ static int ks_pcie_config_legacy_irq(struct keystone_pcie *ks_pcie)
#ifdef CONFIG_ARM
/*
* When a PCI device does not exist during config cycles, keystone host gets a
- * bus error instead of returning 0xffffffff. This handler always returns 0
- * for this kind of faults.
+ * bus error instead of returning 0xffffffff (PCI_ERROR_RESPONSE).
+ * This handler always returns 0 for this kind of faults.
*/
static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
--
2.25.1

2021-10-21 15:20:52

by Naveen Naidu

[permalink] [raw]

Subject: Re: [PATCH v3 17/25] PCI: vmd: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

2021-10-21 15:25:53

by Naveen Naidu

[permalink] [raw]

Subject: Re: [PATCH v3 18/25] PCI: pciehp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

On 21/10, Naveen Naidu wrote:
> An MMIO read from a PCI device that doesn't exist or doesn't respond
> causes a PCI error. There's no real data to return to satisfy the
> CPU read, so most hardware fabricates ~0 data.
>
> Use RESPONSE_IS_PCI_ERROR() to check the response we get when we read
> data from hardware.
>
> This helps unify PCI error response checking and make error checks
> consistent and easier to find.
>
> Compile tested only.
>
> Signed-off-by: Naveen Naidu <[email protected]>
> ---
> drivers/pci/hotplug/pciehp_hpc.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 3024d7e85e6a..f472f83f6cce 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>
> do {
> pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
> - if (slot_status == (u16) ~0) {
> + if (RESPONSE_IS_PCI_ERROR(slot_status)) {
> ctrl_info(ctrl, "%s: no response from device\n",
> __func__);
> return 0;
> @@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd,
> pcie_wait_cmd(ctrl);
>
> pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
> - if (slot_ctrl == (u16) ~0) {
> + if (RESPONSE_IS_PCI_ERROR(slot_ctrl)) {
> ctrl_info(ctrl, "%s: no response from device\n", __func__);
> goto out;
> }
> @@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl)
> int ret;
>
> ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
> - if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0)
> + if (ret == PCIBIOS_DEVICE_NOT_FOUND || RESPONSE_IS_PCI_ERROR(lnk_status))
> return -ENODEV;
>
> ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
> @@ -443,7 +443,7 @@ int pciehp_card_present(struct controller *ctrl)
> int ret;
>
> ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
> - if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0)
> + if (ret == PCIBIOS_DEVICE_NOT_FOUND || RESPONSE_IS_PCI_ERROR(slot_status))
> return -ENODEV;
>
> return !!(slot_status & PCI_EXP_SLTSTA_PDS);
> @@ -621,7 +621,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id)
>
> read_status:
> pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status);
> - if (status == (u16) ~0) {
> + if (RESPONSE_IS_PCI_ERROR(status)) {
> ctrl_info(ctrl, "%s: no response from device\n", __func__);
> if (parent)
> pm_runtime_put(parent);
> --
> 2.25.1
>

Lukas, I have not added your Acked-by tag from the v1 [1] of the patch
series, since the RESPONSE_IS_PCI_ERROR macro definition slightly
changed. I hope this was the right thing to do.

[1]: https://lore.kernel.org/linux-pci/[email protected]/

Also, regarding your comments from v1 patch series [1] about re-naming
the RESPONSE_IS_PCI_ERROR to RESPONSE_IS_PCI_TIMEOUT. We could indeed
change the change to RESPONSE_IS_PCI_TIMEOUT for pciehp, but then
I'm afraid that picehp would be the odd one out. I mean, since in all
the other places we are using RESPONE_IS_PCI_TIMEOUT to see if any
error occured while reading from a device.

RESPONSE_IS_PCI_ERROR stills gives an idea to the readers that some PCI
error occured. It was my understanding that timeout is also a kind of
PCI error (I might be horribly wrong here, given my very less experience
with PCI subsystem) so it would be okay to use RESPONSE_IS_PCI_ERROR
here.

If that is not the case please let me know. But I am not sure what to
do here? If RESPONSE_IS_PCI_ERROR does not fit here, should the right
option would be to revert/remove this patch from the series?

Thanks,
Naveen

2021-10-21 16:00:18

by Pali Rohár

[permalink] [raw]

Subject: Re: [PATCH v3 11/25] PCI: aardvark: Remove redundant error fabrication when device read fails

On Thursday 21 October 2021 20:37:36 Naveen Naidu wrote:
> An MMIO read from a PCI device that doesn't exist or doesn't respond
> causes a PCI error. There's no real data to return to satisfy the
> CPU read, so most hardware fabricates ~0 data.
>
> The host controller drivers sets the error response values (~0) and
> returns an error when faulty hardware read occurs. But the error
> response value (~0) is already being set in PCI_OP_READ and
> PCI_USER_READ_CONFIG whenever a read by host controller driver fails.
>
> Thus, it's no longer necessary for the host controller drivers to
> fabricate any error response.
>
> This helps unify PCI error response checking and make error check
> consistent and easier to find.
>
> Signed-off-by: Naveen Naidu <[email protected]>

Reviewed-by: Pali Rohár <[email protected]>

> ---
> drivers/pci/controller/pci-aardvark.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 596ebcfcc82d..1af772c76d06 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -893,10 +893,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
> u32 reg;
> int ret;
>
> - if (!advk_pcie_valid_device(pcie, bus, devfn)) {
> - *val = 0xffffffff;
> + if (!advk_pcie_valid_device(pcie, bus, devfn))
> return PCIBIOS_DEVICE_NOT_FOUND;
> - }
>
> if (pci_is_root_bus(bus))
> return pci_bridge_emul_conf_read(&pcie->bridge, where,
> @@ -920,7 +918,6 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
> *val = CFG_RD_CRS_VAL;
> return PCIBIOS_SUCCESSFUL;
> }
> - *val = 0xffffffff;
> return PCIBIOS_SET_FAILED;
> }
>
> @@ -955,16 +952,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
> *val = CFG_RD_CRS_VAL;
> return PCIBIOS_SUCCESSFUL;
> }
> - *val = 0xffffffff;
> return PCIBIOS_SET_FAILED;
> }
>
> /* Check PIO status and get the read result */
> ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
> - if (ret < 0) {
> - *val = 0xffffffff;
> + if (ret < 0)
> return PCIBIOS_SET_FAILED;
> - }
>
> if (size == 1)
> *val = (*val >> (8 * (where & 3))) & 0xff;
> --
> 2.25.1
>

2021-10-21 16:03:38

by Pali Rohár

[permalink] [raw]

Subject: Re: [PATCH v3 02/25] PCI: Set error response in config access defines when ops->read() fails

On Thursday 21 October 2021 20:37:27 Naveen Naidu wrote:
> Make PCI_OP_READ and PCI_USER_READ_CONFIG set the data value with error
> response (~0), when the PCI device read by a host controller fails.
>
> This ensures that the controller drivers no longer need to fabricate
> (~0) value when they detect error. It also gurantees that the error
> response (~0) is always set when the controller drivers fails to read a
> config register from a device.
>
> This makes error response fabrication consistent and helps in removal of
> a lot of repeated code.
>
> Suggested-by: Rob Herring <[email protected]>
> Reviewed-by: Rob Herring <[email protected]>
> Signed-off-by: Naveen Naidu <[email protected]>

Reviewed-by: Pali Rohár <[email protected]>

> ---
> drivers/pci/access.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
> index 46935695cfb9..0f732ba2f71a 100644
> --- a/drivers/pci/access.c
> +++ b/drivers/pci/access.c
> @@ -42,7 +42,10 @@ int noinline pci_bus_read_config_##size \
> if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
> pci_lock_config(flags); \
> res = bus->ops->read(bus, devfn, pos, len, &data); \
> - *value = (type)data; \
> + if (res) \
> + SET_PCI_ERROR_RESPONSE(value); \
> + else \
> + *value = (type)data; \
> pci_unlock_config(flags); \
> return res; \
> }
> @@ -228,7 +231,10 @@ int pci_user_read_config_##size \
> ret = dev->bus->ops->read(dev->bus, dev->devfn, \
> pos, sizeof(type), &data); \
> raw_spin_unlock_irq(&pci_lock); \
> - *val = (type)data; \
> + if (ret) \
> + SET_PCI_ERROR_RESPONSE(val); \
> + else \
> + *val = (type)data; \
> return pcibios_err_to_errno(ret); \
> } \
> EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
> --
> 2.25.1
>

2021-10-22 07:04:00

by Lukas Wunner

[permalink] [raw]

Subject: Re: [PATCH v3 18/25] PCI: pciehp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware

On Thu, Oct 21, 2021 at 08:52:53PM +0530, Naveen Naidu wrote:
> Lukas, I have not added your Acked-by tag from the v1 [1] of the patch
> series, since the RESPONSE_IS_PCI_ERROR macro definition slightly
> changed. I hope this was the right thing to do.
[...]
> If that is not the case please let me know. But I am not sure what to
> do here? If RESPONSE_IS_PCI_ERROR does not fit here, should the right
> option would be to revert/remove this patch from the series?

My Acked-by still stands. As for the macro name, I'm fine with
whatever Bjorn and the community settle on. :)

Thanks,

Lukas