Subject: [PATCH v1] drivers/i915/intel_bios: Fix parsing backlight BDB data

Starting BDB version 239, hdr_dpcd_refresh_timeout is introduced to
backlight BDB data. Commit 700034566d68 ("drm/i915/bios: Define more BDB
contents") updated the backlight BDB data accordingly. This broke the
parsing of backlight BDB data in VBT for versions 236 - 238 (both
inclusive) and hence the backlight controls are not responding on units
with the concerned BDB version.

backlight_control information has been present in backlight BDB data
from at least BDB version 191 onwards, if not before. Hence this patch
extracts the backlight_control information if the block size of
backlight BDB is >= version 191 backlight BDB block size.
Tested on Chromebooks using Jasperlake SoC (reports bdb->version = 236).
Tested on Chromebooks using Raptorlake SoC (reports bdb->version = 251).

Fixes: 700034566d68 ("drm/i915/bios: Define more BDB contents")
Cc: [email protected]
Cc: Jani Nikula <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Signed-off-by: Karthikeyan Ramasubramanian <[email protected]>
---

drivers/gpu/drm/i915/display/intel_bios.c | 22 +++++--------------
drivers/gpu/drm/i915/display/intel_vbt_defs.h | 2 --
2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index aa169b0055e97..4ec50903b9e64 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -1041,23 +1041,13 @@ parse_lfp_backlight(struct drm_i915_private *i915,

panel->vbt.backlight.type = INTEL_BACKLIGHT_DISPLAY_DDI;
panel->vbt.backlight.controller = 0;
- if (i915->display.vbt.version >= 191) {
- size_t exp_size;
+ if (i915->display.vbt.version >= 191 &&
+ get_blocksize(backlight_data) >= EXP_BDB_LFP_BL_DATA_SIZE_REV_191) {
+ const struct lfp_backlight_control_method *method;

- if (i915->display.vbt.version >= 236)
- exp_size = sizeof(struct bdb_lfp_backlight_data);
- else if (i915->display.vbt.version >= 234)
- exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_234;
- else
- exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_191;
-
- if (get_blocksize(backlight_data) >= exp_size) {
- const struct lfp_backlight_control_method *method;
-
- method = &backlight_data->backlight_control[panel_type];
- panel->vbt.backlight.type = method->type;
- panel->vbt.backlight.controller = method->controller;
- }
+ method = &backlight_data->backlight_control[panel_type];
+ panel->vbt.backlight.type = method->type;
+ panel->vbt.backlight.controller = method->controller;
}

panel->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;
diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
index a9f44abfc9fc2..aeea5635a37ff 100644
--- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
+++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
@@ -899,8 +899,6 @@ struct lfp_brightness_level {

#define EXP_BDB_LFP_BL_DATA_SIZE_REV_191 \
offsetof(struct bdb_lfp_backlight_data, brightness_level)
-#define EXP_BDB_LFP_BL_DATA_SIZE_REV_234 \
- offsetof(struct bdb_lfp_backlight_data, brightness_precision_bits)

struct bdb_lfp_backlight_data {
u8 entry_size;
--
2.44.0.rc0.258.g7320e95886-goog



2024-02-21 18:20:37

by Ville Syrjälä

[permalink] [raw]
Subject: Re: [PATCH v1] drivers/i915/intel_bios: Fix parsing backlight BDB data

On Tue, Feb 20, 2024 at 02:12:57PM -0700, Karthikeyan Ramasubramanian wrote:
> Starting BDB version 239, hdr_dpcd_refresh_timeout is introduced to
> backlight BDB data. Commit 700034566d68 ("drm/i915/bios: Define more BDB
> contents") updated the backlight BDB data accordingly. This broke the
> parsing of backlight BDB data in VBT for versions 236 - 238 (both
> inclusive) and hence the backlight controls are not responding on units
> with the concerned BDB version.
>
> backlight_control information has been present in backlight BDB data
> from at least BDB version 191 onwards, if not before. Hence this patch
> extracts the backlight_control information if the block size of
> backlight BDB is >= version 191 backlight BDB block size.
> Tested on Chromebooks using Jasperlake SoC (reports bdb->version = 236).
> Tested on Chromebooks using Raptorlake SoC (reports bdb->version = 251).
>
> Fixes: 700034566d68 ("drm/i915/bios: Define more BDB contents")
> Cc: [email protected]
> Cc: Jani Nikula <[email protected]>
> Cc: Ville Syrj?l? <[email protected]>
> Signed-off-by: Karthikeyan Ramasubramanian <[email protected]>
> ---
>
> drivers/gpu/drm/i915/display/intel_bios.c | 22 +++++--------------
> drivers/gpu/drm/i915/display/intel_vbt_defs.h | 2 --
> 2 files changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index aa169b0055e97..4ec50903b9e64 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -1041,23 +1041,13 @@ parse_lfp_backlight(struct drm_i915_private *i915,
>
> panel->vbt.backlight.type = INTEL_BACKLIGHT_DISPLAY_DDI;
> panel->vbt.backlight.controller = 0;
> - if (i915->display.vbt.version >= 191) {
> - size_t exp_size;
> + if (i915->display.vbt.version >= 191 &&
> + get_blocksize(backlight_data) >= EXP_BDB_LFP_BL_DATA_SIZE_REV_191) {

The size checks looks like nonsense to me. I guess maybe
we needed it before we were guaranteed to have the full
struct's worth of memory. But there should be no need for
this anymore.

> + const struct lfp_backlight_control_method *method;
>
> - if (i915->display.vbt.version >= 236)
> - exp_size = sizeof(struct bdb_lfp_backlight_data);
> - else if (i915->display.vbt.version >= 234)
> - exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_234;
> - else
> - exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_191;
> -
> - if (get_blocksize(backlight_data) >= exp_size) {
> - const struct lfp_backlight_control_method *method;
> -
> - method = &backlight_data->backlight_control[panel_type];
> - panel->vbt.backlight.type = method->type;
> - panel->vbt.backlight.controller = method->controller;
> - }
> + method = &backlight_data->backlight_control[panel_type];
> + panel->vbt.backlight.type = method->type;
> + panel->vbt.backlight.controller = method->controller;
> }
>
> panel->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;
> diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> index a9f44abfc9fc2..aeea5635a37ff 100644
> --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> @@ -899,8 +899,6 @@ struct lfp_brightness_level {
>
> #define EXP_BDB_LFP_BL_DATA_SIZE_REV_191 \
> offsetof(struct bdb_lfp_backlight_data, brightness_level)
> -#define EXP_BDB_LFP_BL_DATA_SIZE_REV_234 \
> - offsetof(struct bdb_lfp_backlight_data, brightness_precision_bits)
>
> struct bdb_lfp_backlight_data {
> u8 entry_size;
> --
> 2.44.0.rc0.258.g7320e95886-goog

--
Ville Syrj?l?
Intel