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[108.49.102.102]) by smtp.gmail.com with ESMTPSA id g1sm2485892qtp.74.2020.10.07.14.53.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 14:53:22 -0700 (PDT) Message-ID: <268f495fbb7e3042eb613398a8513a83d28d3fd9.camel@redhat.com> Subject: Re: [PATCH 1/2] drm/i915/dpcd_bl: Skip testing control capability with force DPCD quirk From: Lyude Paul Reply-To: lyude@redhat.com To: Satadru Pramanik , Kai-Heng Feng , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Ville =?ISO-8859-1?Q?Syrj=E4l=E4?= , Juha-Pekka Heikkila , intel-gfx@lists.freedesktop.org, "open list:DRM DRIVERS" , open list Date: Wed, 07 Oct 2020 17:53:21 -0400 In-Reply-To: <20201007065915.13883-1-kai.heng.feng@canonical.com> References: <20201007065915.13883-1-kai.heng.feng@canonical.com> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! I thought this patch rang a bell, we actually already had some discussion about this since there's a couple of other systems this was causing issues for. Unfortunately it never seems like that patch got sent out. Satadru? (if I don't hear back from them soon, I'll just send out a patch for this myself) JFYI - the proper fix here is to just drop the DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP check from the code entirely. As long as the backlight supports AUX_SET_CAP, that should be enough for us to control it. On Wed, 2020-10-07 at 14:58 +0800, Kai-Heng Feng wrote: > 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 > --- > 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 " -- Sincerely, Lyude Paul (she/her) Software Engineer at Red Hat