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: stable@xxxxxxxxxxxxxxx
> Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Signed-off-by: Karthikeyan Ramasubramanian <kramasub@xxxxxxxxxxxx>
> ---
>
> 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 Syrjälä
Intel
