drm/i915/backlight: Check if VESA backlight is possible

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Check if BACKLIGHT_BRIGHTNESS_AUX_SET_CAPABLE bit is
set then EDP_PWMGEN_BIT_COUNT_CAP_MIN and EDP_PWMGEN_BIT_COUNT_CAP_MAX
follow the eDP 1.4b Section 10.3. Which states min should
be >= 1 and max should be >= min. Some legacy panels
do not follow this properly. They set the
BACKLIGHT_BRIGHTNESS_AUX_SET_CAPABLE bit while not correctly
populating the min and max fields leading to a 0 max value.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/7514
Fixes: 40d2f58209 ("drm/i915/backlight: Remove try_vesa_interface")
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Pranay Samala <pranay.samala@intel.com>
Link: https://patch.msgid.link/20260316031850.81794-1-suraj.kandpal@intel.com

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Suraj Kandpal 2026-03-16 08:48:51 +05:30

parent 3ccc8a9229

commit 0fb03890d1

1 changed files with 31 additions and 1 deletions

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

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