Commit 4378daf5 authored by Lukasz Majczak's avatar Lukasz Majczak Committed by José Roberto de Souza
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drm/i915/bdb: Fix version check 



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: d381baad ("drm/i915/vbt: Fix backlight parsing for VBT 234+")

Tested-by: default avatarLukasz Majczak <lma@semihalf.com>
Signed-off-by: default avatarLukasz Majczak <lma@semihalf.com>
Reviewed-by: default avatarJosé Roberto de Souza <jose.souza@intel.com>
Signed-off-by: default avatarJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210930134606.227234-1-lma@semihalf.com
parent f0b6b01b

drivers/gpu/drm/i915/display/intel_bios.c

+16 −6
Original line number Diff line number Diff line
@@ -451,14 +451,24 @@ 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)) {

	if (bdb->version >= 191) {

		size_t exp_size;



		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;

	i915->vbt.backlight.active_low_pwm = entry->active_low_pwm;

drivers/gpu/drm/i915/display/intel_vbt_defs.h

+5 −0
Original line number Diff line number Diff line
@@ -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];