From: Suraj Kandpal Date: Tue, 7 Apr 2026 03:07:11 +0000 (+0530) Subject: drm/i915/backlight: Fix VESA backlight possible check condition X-Git-Tag: v7.1-rc1~53^2~1^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed8be780bdbc9f7727553b9fa6951f5c38b0a15b;p=thirdparty%2Fkernel%2Flinux.git drm/i915/backlight: Fix VESA backlight possible check condition VESA backlight enable is possible when BACKLIGHT_AUX_ENABLE_CAPABLE is true via AUX command or when BACKLIGHT_PIN_ENABLE_CAPABLE is true via eDP connector pin. Similarly, backlight brightness adjustment can be done via AUX-based control or PWM pin-based control. It means there can be three configurations: 1) Full AUX-based: Enable and adjustment both via AUX. We currently support this (apart from the AUX luminance-based backlight control). 2) Hybrid: Enable via the BL_ENABLE pin, adjustment via either AUX or PWM. 3) Fully PWM pin-based: Enable via the BL_ENABLE pin, adjustment via PWM. Since that only 1 is supported as of now we need to make sure we do not try to manipulate backlight when BACKLIGHT_AUX_ENABLE_CAPABLE is not set. Also fix return value when condition is not fulfilled. Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/15907 Fixes: 0fb03890d182 ("drm/i915/backlight: Check if VESA backlight is possible") Signed-off-by: Suraj Kandpal Tested-by: Ville Syrjälä Reviewed-by: Ankit Nautiyal Link: https://patch.msgid.link/20260407030710.1440046-1-suraj.kandpal@intel.com (cherry picked from commit 102d44b3a8fad96e94e9ccd0579986c14a1f2f75) Signed-off-by: Tvrtko Ursulin --- diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index d0c76632a946a..a8d56ebf06a2f 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -615,8 +615,13 @@ check_if_vesa_backlight_possible(struct intel_dp *intel_dp) int ret; u8 bit_min, bit_max; - if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) - return true; + /* + * Since we only support Fully AUX Based VESA Backlight interface make sure + * backlight enable is possible via AUX along with backlight adjustment + */ + if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP && + intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) + return false; ret = drm_dp_dpcd_read_byte(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &bit_min); if (ret < 0)