From: Lyude Paul <lyude@xxxxxxxxxx> Annoyingly, the VBT on the ThinkPad X1 Extreme 2nd Gen indicates that the system uses plain PWM based backlight controls, when in reality the only backlight controls that work are the standard VESA eDP DPCD backlight controls. Honestly, this makes me wonder how many other systems have these issues or lie about this in their VBT. Not sure we have any good way of finding out until panels like this become more common place in the laptop market. For now, just add a DRM DP quirk to indicate that this panel is telling the truth and is being a good LCD. v2 by Jani: - rebase Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112376 Closes: https://gitlab.freedesktop.org/drm/intel/issues/642 Tested-by: AceLan Kao <acelan.kao@xxxxxxxxxxxxx> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> --- drivers/gpu/drm/drm_dp_helper.c | 4 ++++ drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 8 ++++++-- include/drm/drm_dp_helper.h | 8 ++++++++ 3 files changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 5a103e9b3c86..90e122809fa4 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -1179,6 +1179,10 @@ static const struct dpcd_quirk dpcd_quirk_list[] = { { OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) }, /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */ { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) }, + /* Optional 4K AMOLED panel in the ThinkPad X1 Extreme 2nd Generation + * only supports DPCD backlight controls, despite advertising otherwise + */ + { OUI(0xba, 0x41, 0x59), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_FORCE_DPCD_BACKLIGHT) }, }; #undef OUI 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 77a759361c5c..57774003e8c5 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -328,11 +328,15 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector) int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector) { struct intel_panel *panel = &intel_connector->panel; - struct drm_i915_private *dev_priv = to_i915(intel_connector->base.dev); + struct intel_dp *intel_dp = enc_to_intel_dp(intel_connector->encoder); + struct drm_i915_private *i915 = to_i915(intel_connector->base.dev); if (i915_modparams.enable_dpcd_backlight == 0 || (i915_modparams.enable_dpcd_backlight == -1 && - dev_priv->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)) + i915->vbt.backlight.type != + INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE && + !drm_dp_has_quirk(&intel_dp->desc, + DP_DPCD_QUIRK_FORCE_DPCD_BACKLIGHT))) return -ENODEV; if (!intel_dp_aux_display_control_capable(intel_connector)) diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 262faf9e5e94..bb081921f53d 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1532,6 +1532,14 @@ enum drm_dp_quirk { * The DSC caps can be read from the physical aux instead. */ DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD, + /** + * @DP_DPCD_QUIRK_FORCE_DPCD_BACKLIGHT: + * + * The device is telling the truth when it says that it uses DPCD + * backlight controls, even if the system's firmware disagrees. + * The driver should honor the DPCD backlight capabilities advertised. + */ + DP_DPCD_QUIRK_FORCE_DPCD_BACKLIGHT, }; /** -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
