[PATCH 6.8 304/336] drm/i915/bios: Fix parsing backlight BDB data

Greg Kroah-Hartman
2024-05-14T10:53:04Z

From: Karthikeyan Ramasubramanian <kramasub@chromium.org>

commit 43b26bdd2ee5cfca80939be910d5b23a50cd7f9d upstream.

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 for BDB version 191 or newer.
Tested on Chromebooks using Jasperlake SoC (reports bdb->version = 236).
Tested on Chromebooks using Raptorlake SoC (reports bdb->version = 251).

v2: removed checking the block size of the backlight BDB data
[vsyrjala: this is completely safe thanks to commit e163cfb4c96d
("drm/i915/bios: Make copies of VBT data blocks")]

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>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240221180622.v2.1.I0690aa3e96a83a43b3fc33f50395d334b2981826@changeid
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
(cherry picked from commit c286f6a973c66c0d993ecab9f7162c790e7064c8)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/i915/display/intel_bios.c | 19 ++++---------------
drivers/gpu/drm/i915/display/intel_vbt_defs.h | 5 -----
2 files changed, 4 insertions(+), 20 deletions(-)

--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -1042,22 +1042,11 @@ parse_lfp_backlight(struct drm_i915_priv
panel->vbt.backlight.type = INTEL_BACKLIGHT_DISPLAY_DDI;
panel->vbt.backlight.controller = 0;
if (i915->display.vbt.version >= 191) {
- size_t exp_size;
+ 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;
--- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
+++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
@@ -897,11 +897,6 @@ 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];