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@vger.kernel.org Cc: Jani Nikula jani.nikula@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Karthikeyan Ramasubramanian kramasub@chromium.org

---

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