On Thu, Oct 19, 2017 at 12:32 PM, Rob Clark <robdclark@xxxxxxxxx> wrote: > On Wed, Oct 18, 2017 at 4:06 PM, Lloyd Atkinson <latkinso@xxxxxxxxxxxxxx> wrote: >> Hi folks, >> >> We're looking at 4K HDMI mode support, and noticed aspect ratio support >> is in flux. >> >> Aspect ratio parsing was added to the mode: >> https://patchwork.kernel.org/patch/9271401/ >> >> But later reverted: >> https://patchwork.kernel.org/patch/9410765/ >> >> We're finding that since aspect ratio information isn't supported, modes >> conflict, and the userspace isn't able to see the full list of modes. >> >> Similarly, there's a case where two modes differ only by aspect_ratio >> and vrefresh. In drm_edid.c, within drm_display_mode_from_vic_index, >> newmode->vrefresh is forcibly being cleared to 0. Since refresh rate is >> forced to 0, and aspect ratio isn’t considered in general, the modes >> collide and we can’t advertise one of the modes. >> >> https://github.com/torvalds/linux/blob/v4.14-rc4/drivers/gpu/drm/drm_edid.c#L3153 >> >> Have there been any follow-up discussions on this topic? >> >> What is the reason to clear the vrefresh within >> drm_display_mode_from_vic_index? > > +Ville who might remember the history.. > > I don't remember if we found a userspace app that was broken, or if > reverting was an "abundance of caution" thing (which is equally valid, > it is basically impossible to track down and test "all of > userspace"..) > Wasn't there an issue with SNA? Alex > Adding a cap to let userspace opt-in to the new behaviour seems like a > sensible approach, and one that we've used before.> > BR, > -R > >> Thanks, >> Lloyd Atkinson >> >> -- >> QUALCOMM Canada, on behalf of Qualcomm Innovation Center, Inc. is a member >> of Code Aurora Forum, hosted by The Linux Foundation >> _______________________________________________ >> dri-devel mailing list >> dri-devel@xxxxxxxxxxxxxxxxxxxxx >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
