From: Lukasz Majczak lma@semihalf.com
[ Upstream commit fdddf8c3a477f77b3a623f220e78d45e89fc50d5 ]
With patch "drm/i915/vbt: Fix backlight parsing for VBT 234+" the size of bdb_lfp_backlight_data structure has been increased, causing if-statement in the parse_lfp_backlight function that comapres this structure size to the one retrieved from BDB, always to fail for older revisions. This patch calculates expected size of the structure for a given BDB version and compares it with the value gathered from BDB. Tested on Chromebook Pixelbook (Nocturne) (reports bdb->version = 221)
Fixes: d381baad29b4 ("drm/i915/vbt: Fix backlight parsing for VBT 234+")
Tested-by: Lukasz Majczak lma@semihalf.com Signed-off-by: Lukasz Majczak lma@semihalf.com Reviewed-by: José Roberto de Souza jose.souza@intel.com Signed-off-by: José Roberto de Souza jose.souza@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20210930134606.227234-1-lma@se... (cherry picked from commit 4378daf5d04eed59724e6d0e74755e17dce2e105) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/display/intel_bios.c | 22 ++++++++++++++----- drivers/gpu/drm/i915/display/intel_vbt_defs.h | 5 +++++ 2 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c index aa667fa71158..106f696e50a0 100644 --- a/drivers/gpu/drm/i915/display/intel_bios.c +++ b/drivers/gpu/drm/i915/display/intel_bios.c @@ -451,13 +451,23 @@ parse_lfp_backlight(struct drm_i915_private *i915, }
i915->vbt.backlight.type = INTEL_BACKLIGHT_DISPLAY_DDI; - if (bdb->version >= 191 && - get_blocksize(backlight_data) >= sizeof(*backlight_data)) { - const struct lfp_backlight_control_method *method; + if (bdb->version >= 191) { + size_t exp_size;
- method = &backlight_data->backlight_control[panel_type]; - i915->vbt.backlight.type = method->type; - i915->vbt.backlight.controller = method->controller; + if (bdb->version >= 236) + exp_size = sizeof(struct bdb_lfp_backlight_data); + else if (bdb->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]; + i915->vbt.backlight.type = method->type; + i915->vbt.backlight.controller = method->controller; + } }
i915->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 dbe24d7e7375..cf1ffe4a0e46 100644 --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h @@ -814,6 +814,11 @@ struct lfp_brightness_level { u16 reserved; } __packed;
+#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; struct lfp_backlight_data_entry data[16];