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)
Tested-by: Lukasz Majczak <lma@xxxxxxxxxxxx>
Signed-off-by: Lukasz Majczak <lma@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_bios.c | 11 +++++++++--
drivers/gpu/drm/i915/display/intel_vbt_defs.h | 5 +++++
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 3c25926092de..90eae6da12e0 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -428,6 +428,7 @@ parse_lfp_backlight(struct drm_i915_private *i915,
const struct lfp_backlight_data_entry *entry;
int panel_type = i915->vbt.panel_type;
u16 level;
+ size_t exp_size;
backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
if (!backlight_data)
@@ -450,9 +451,15 @@ parse_lfp_backlight(struct drm_i915_private *i915,
return;
}
+ if (bdb->version <= 234)
+ exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_234;
+ else if (bdb->version > 234 && bdb->version <= 236)
+ exp_size = EXP_BDB_LFP_BL_DATA_SIZE_REV_236;
+ else
+ exp_size = sizeof(struct bdb_lfp_backlight_data);
+
i915->vbt.backlight.type = INTEL_BACKLIGHT_DISPLAY_DDI;
- if (bdb->version >= 191 &&
- get_blocksize(backlight_data) >= sizeof(*backlight_data)) {
+ if (bdb->version >= 191 && get_blocksize(backlight_data) >= exp_size) {
const struct lfp_backlight_control_method *method;
method = &backlight_data->backlight_control[panel_type];
diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
index 330077c2e588..ba9990e5983c 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_234 \
+ offsetof(struct bdb_lfp_backlight_data, brightness_level)
+#define EXP_BDB_LFP_BL_DATA_SIZE_REV_236 \
+ offsetof(struct bdb_lfp_backlight_data, brightness_precision_bits)
+
struct bdb_lfp_backlight_data {
u8 entry_size;
struct lfp_backlight_data_entry data[16];
--
2.33.0.464.g1972c5931b-goog
