[PATCH 1/2] drm/i915/dpcd_bl: Skip testing control capability with force DPCD quirk

[Kai-Heng Feng]

HP DreamColor panel needs to be controlled via AUX interface. However,
it has both DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP and
DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP set, so it fails to pass
intel_dp_aux_display_control_capable() test.

Skip the test if the panel has force DPCD quirk.

Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

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 acbd7eb66cbe..acf2e1c65290 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -347,9 +347,13 @@ int intel_dp_aux_init_backlight_funcs(struct 
intel_connector *intel_connector)
        struct intel_panel *panel = &intel_connector->panel;
        struct intel_dp *intel_dp = enc_to_intel_dp(intel_connector->encoder);
        struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+       bool force_dpcd;
+
+       force_dpcd = drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,
+                                     DP_QUIRK_FORCE_DPCD_BACKLIGHT);
 
        if (i915->params.enable_dpcd_backlight == 0 ||
-           !intel_dp_aux_display_control_capable(intel_connector))
+           (!force_dpcd && 
!intel_dp_aux_display_control_capable(intel_connector)))
                return -ENODEV;
 
        /*
@@ -358,9 +362,7 @@ int intel_dp_aux_init_backlight_funcs(struct 
intel_connector *intel_connector)
         */
        if (i915->vbt.backlight.type !=
            INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE &&
-           i915->params.enable_dpcd_backlight != 1 &&
-           !drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,
-                             DP_QUIRK_FORCE_DPCD_BACKLIGHT)) {
+           i915->params.enable_dpcd_backlight != 1 && !force_dpcd) {
                drm_info(&i915->drm,
                         "Panel advertises DPCD backlight support, but "
                         "VBT disagrees. If your backlight controls "
-- 
2.17.1