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 | 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 3c25926092de..f9776ca85de3 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 330077c2e588..a2108a8f544d 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];
--
2.33.0.685.g46640cef36-goog
