| Message ID | 1464273544-23834-2-git-send-email-mario.kleiner.de@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, May 26, 2016 at 4:39 PM, Mario Kleiner <mario.kleiner.de@gmail.com> wrote: > This reverts commit 013dd9e03872 > ("drm/i915/dp: fall back to 18 bpp when sink capability is unknown") > > This commit introduced a regression into stable kernels, > as it reduces output color depth to 6 bpc for any video > sink connected to a Displayport connector if that sink > doesn't report a specific color depth via EDID, or if > our EDID parser doesn't actually recognize the proper > bpc from EDID. > > Affected are active DisplayPort->VGA converters and > active DisplayPort->DVI converters. Both should be > able to handle 8 bpc, but are degraded to 6 bpc with > this patch. > > The reverted commit was meant to fix > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331 > > A followup patch implements a fix for that specific bug, > which is caused by a faulty EDID of the affected DP panel > by adding a new EDID quirk for that panel. > > DP 18 bpp fallback handling and other improvements to > DP sink bpc detection will be handled for future > kernels in a separate series of patches. > > Please backport to stable. > > Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> > Acked-by: Jani Nikula <jani.nikula@intel.com> > Cc: stable@vger.kernel.org > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> I wonder whether we shouldn't just move this into the DP code, and instead of looking at the edid (which is just pass-through for dp->vga dongles) we should only look at dpcd values? Or maybe only look at the edid value if the sink is native DP, and not when it's a dongle. That would probably also avoid the quirk, and that quirk seems a bit fishy. -Daniel
On 06/14/2016 01:05 PM, Daniel Vetter wrote: > On Thu, May 26, 2016 at 4:39 PM, Mario Kleiner > <mario.kleiner.de@gmail.com> wrote: >> This reverts commit 013dd9e03872 >> ("drm/i915/dp: fall back to 18 bpp when sink capability is unknown") >> >> This commit introduced a regression into stable kernels, >> as it reduces output color depth to 6 bpc for any video >> sink connected to a Displayport connector if that sink >> doesn't report a specific color depth via EDID, or if >> our EDID parser doesn't actually recognize the proper >> bpc from EDID. >> >> Affected are active DisplayPort->VGA converters and >> active DisplayPort->DVI converters. Both should be >> able to handle 8 bpc, but are degraded to 6 bpc with >> this patch. >> >> The reverted commit was meant to fix >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331 >> >> A followup patch implements a fix for that specific bug, >> which is caused by a faulty EDID of the affected DP panel >> by adding a new EDID quirk for that panel. >> >> DP 18 bpp fallback handling and other improvements to >> DP sink bpc detection will be handled for future >> kernels in a separate series of patches. >> >> Please backport to stable. >> >> Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> >> Acked-by: Jani Nikula <jani.nikula@intel.com> >> Cc: stable@vger.kernel.org >> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > I wonder whether we shouldn't just move this into the DP code, and > instead of looking at the edid (which is just pass-through for dp->vga > dongles) we should only look at dpcd values? Or maybe only look at the > edid value if the sink is native DP, and not when it's a dongle. > > That would probably also avoid the quirk, and that quirk seems a bit fishy. > -Daniel > This patch is just a simple fix for the color depth regression which affects stable kernels. It can be back-ported easily to affected stable kernels, as Jani advised me. I wanted to clean up and resubmit that DP helper function which looks at dpcd values and might be a bit too much for stable, once this fix is in. -mario
Any news on this one? Thanks a bunch, -mario On 06/14/2016 04:12 PM, Mario Kleiner wrote: > On 06/14/2016 01:05 PM, Daniel Vetter wrote: >> On Thu, May 26, 2016 at 4:39 PM, Mario Kleiner >> <mario.kleiner.de@gmail.com> wrote: >>> This reverts commit 013dd9e03872 >>> ("drm/i915/dp: fall back to 18 bpp when sink capability is unknown") >>> >>> This commit introduced a regression into stable kernels, >>> as it reduces output color depth to 6 bpc for any video >>> sink connected to a Displayport connector if that sink >>> doesn't report a specific color depth via EDID, or if >>> our EDID parser doesn't actually recognize the proper >>> bpc from EDID. >>> >>> Affected are active DisplayPort->VGA converters and >>> active DisplayPort->DVI converters. Both should be >>> able to handle 8 bpc, but are degraded to 6 bpc with >>> this patch. >>> >>> The reverted commit was meant to fix >>> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331 >>> >>> A followup patch implements a fix for that specific bug, >>> which is caused by a faulty EDID of the affected DP panel >>> by adding a new EDID quirk for that panel. >>> >>> DP 18 bpp fallback handling and other improvements to >>> DP sink bpc detection will be handled for future >>> kernels in a separate series of patches. >>> >>> Please backport to stable. >>> >>> Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> >>> Acked-by: Jani Nikula <jani.nikula@intel.com> >>> Cc: stable@vger.kernel.org >>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> >>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> I wonder whether we shouldn't just move this into the DP code, and >> instead of looking at the edid (which is just pass-through for dp->vga >> dongles) we should only look at dpcd values? Or maybe only look at the >> edid value if the sink is native DP, and not when it's a dongle. >> >> That would probably also avoid the quirk, and that quirk seems a bit >> fishy. >> -Daniel >> > > This patch is just a simple fix for the color depth regression which > affects stable kernels. It can be back-ported easily to affected stable > kernels, as Jani advised me. > > I wanted to clean up and resubmit that DP helper function which looks at > dpcd values and might be a bit too much for stable, once this fix is in. > > -mario
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 46f9be3..3a57fa1 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12066,21 +12066,11 @@ connected_sink_compute_bpp(struct intel_connector *connector, pipe_config->pipe_bpp = connector->base.display_info.bpc*3; } - /* Clamp bpp to default limit on screens without EDID 1.4 */ - if (connector->base.display_info.bpc == 0) { - int type = connector->base.connector_type; - int clamp_bpp = 24; - - /* Fall back to 18 bpp when DP sink capability is unknown. */ - if (type == DRM_MODE_CONNECTOR_DisplayPort || - type == DRM_MODE_CONNECTOR_eDP) - clamp_bpp = 18; - - if (bpp > clamp_bpp) { - DRM_DEBUG_KMS("clamping display bpp (was %d) to default limit of %d\n", - bpp, clamp_bpp); - pipe_config->pipe_bpp = clamp_bpp; - } + /* Clamp bpp to 8 on screens without EDID 1.4 */ + if (connector->base.display_info.bpc == 0 && bpp > 24) { + DRM_DEBUG_KMS("clamping display bpp (was %d) to default limit of 24\n", + bpp); + pipe_config->pipe_bpp = 24; } }
This reverts commit 013dd9e03872 ("drm/i915/dp: fall back to 18 bpp when sink capability is unknown") This commit introduced a regression into stable kernels, as it reduces output color depth to 6 bpc for any video sink connected to a Displayport connector if that sink doesn't report a specific color depth via EDID, or if our EDID parser doesn't actually recognize the proper bpc from EDID. Affected are active DisplayPort->VGA converters and active DisplayPort->DVI converters. Both should be able to handle 8 bpc, but are degraded to 6 bpc with this patch. The reverted commit was meant to fix Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331 A followup patch implements a fix for that specific bug, which is caused by a faulty EDID of the affected DP panel by adding a new EDID quirk for that panel. DP 18 bpp fallback handling and other improvements to DP sink bpc detection will be handled for future kernels in a separate series of patches. Please backport to stable. Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Cc: stable@vger.kernel.org Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/intel_display.c | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-)