<div dir="ltr">Kevin Chowski said he would be geting to working on upstreaming a version of that which was in the ChromeOS tree here: <div><br></div><div><a href="https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2344844">https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2344844</a> when I last spoke to hi<div><br></div><div>(This was two weeks ago.)</div></div><div><br></div><div>Kevin - do you have any input on this?</div><div><br></div><div>Satadru</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Oct 8, 2020 at 1:07 PM Lyude Paul <<a href="mailto:lyude@redhat.com" target="_blank">lyude@redhat.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">oh hold on, I misspoke. Here's the patch I was thinking of:<br>
<br>
<a href="https://patchwork.freedesktop.org/series/82041/" rel="noreferrer" target="_blank">https://patchwork.freedesktop.org/series/82041/</a><br>
<br>
On Thu, 2020-10-08 at 10:32 +0800, Kai-Heng Feng wrote:<br>
> Hi Lyude,<br>
> <br>
> > On Oct 8, 2020, at 05:53, Lyude Paul <<a href="mailto:lyude@redhat.com" target="_blank">lyude@redhat.com</a>> wrote:<br>
> > <br>
> > Hi! I thought this patch rang a bell, we actually already had some<br>
> > discussion<br>
> > about this since there's a couple of other systems this was causing issues<br>
> > for.<br>
> > Unfortunately it never seems like that patch got sent out. Satadru?<br>
> > <br>
> > (if I don't hear back from them soon, I'll just send out a patch for this<br>
> > myself)<br>
> > <br>
> > JFYI - the proper fix here is to just drop the<br>
> > DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP check from the code entirely. As<br>
> > long as<br>
> > the backlight supports AUX_SET_CAP, that should be enough for us to control<br>
> > it.<br>
> <br>
> Does the proper fix include dropping DP_QUIRK_FORCE_DPCD_BACKLIGHT entirely?<br>
> <br>
> Kai-Heng<br>
> <br>
> > <br>
> > On Wed, 2020-10-07 at 14:58 +0800, Kai-Heng Feng wrote:<br>
> > > HP DreamColor panel needs to be controlled via AUX interface. However,<br>
> > > it has both DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP and<br>
> > > DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP set, so it fails to pass<br>
> > > intel_dp_aux_display_control_capable() test.<br>
> > > <br>
> > > Skip the test if the panel has force DPCD quirk.<br>
> > > <br>
> > > Signed-off-by: Kai-Heng Feng <<a href="mailto:kai.heng.feng@canonical.com" target="_blank">kai.heng.feng@canonical.com</a>><br>
> > > ---<br>
> > > drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 10 ++++++----<br>
> > > 1 file changed, 6 insertions(+), 4 deletions(-)<br>
> > > <br>
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c<br>
> > > b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c<br>
> > > index acbd7eb66cbe..acf2e1c65290 100644<br>
> > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c<br>
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c<br>
> > > @@ -347,9 +347,13 @@ int intel_dp_aux_init_backlight_funcs(struct<br>
> > > intel_connector *intel_connector)<br>
> > > struct intel_panel *panel = &intel_connector->panel;<br>
> > > struct intel_dp *intel_dp = enc_to_intel_dp(intel_connector->encoder);<br>
> > > struct drm_i915_private *i915 = dp_to_i915(intel_dp);<br>
> > > + bool force_dpcd;<br>
> > > +<br>
> > > + force_dpcd = drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,<br>
> > > + DP_QUIRK_FORCE_DPCD_BACKLIGHT);<br>
> > > <br>
> > > if (i915->params.enable_dpcd_backlight == 0 ||<br>
> > > - !intel_dp_aux_display_control_capable(intel_connector))<br>
> > > + (!force_dpcd &&<br>
> > > !intel_dp_aux_display_control_capable(intel_connector)))<br>
> > > return -ENODEV;<br>
> > > <br>
> > > /*<br>
> > > @@ -358,9 +362,7 @@ int intel_dp_aux_init_backlight_funcs(struct<br>
> > > intel_connector *intel_connector)<br>
> > > */<br>
> > > if (i915->vbt.backlight.type !=<br>
> > > INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE &&<br>
> > > - i915->params.enable_dpcd_backlight != 1 &&<br>
> > > - !drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,<br>
> > > - DP_QUIRK_FORCE_DPCD_BACKLIGHT)) {<br>
> > > + i915->params.enable_dpcd_backlight != 1 && !force_dpcd) {<br>
> > > drm_info(&i915->drm,<br>
> > > "Panel advertises DPCD backlight support, but "<br>
> > > "VBT disagrees. If your backlight controls "<br>
> > -- <br>
> > Sincerely,<br>
> > Lyude Paul (she/her)<br>
> > Software Engineer at Red Hat<br>
-- <br>
Sincerely,<br>
Lyude Paul (she/her)<br>
Software Engineer at Red Hat<br>
<br>
</blockquote></div>