On Fri, Oct 11, 2019 at 04:51:13PM -0400, Lyude Paul wrote: > a little late but: i915 does have this hack (or rather-possible_crtcs with MST > in i915 has been broken for a while and got fixed, but had to get reverted > because of this issue), it's where this originally came from. Hm since this is widespread I think we should check for this when we register connectors (either in drm_dev_register, or hotplugged ones). I think just validating that all encoder->possible_crtc match and WARN_ON if not would be really good. 2nd option would be to do that in the GETENCODERS ioctl. That would at least keep the encoders useful for driver-internal stuff. We could then un-revert the i915 patch again. Either way I think we should have this hack + comment with links to the offending userspace in common code, not duplicated over all drivers. -Daniel > > On Wed, 2019-10-09 at 17:01 +0200, Daniel Vetter wrote: > > On Fri, Sep 27, 2019 at 11:27:41AM -0400, Sean Paul wrote: > > > On Thu, Sep 26, 2019 at 06:51:07PM -0400, Lyude Paul wrote: > > > > This commit is seperate from the previous one to make it easier to > > > > revert in the future. Basically, there's multiple userspace applications > > > > that interpret possible_crtcs very wrong: > > > > > > > > https://gitlab.freedesktop.org/xorg/xserver/merge_requests/277 > > > > https://gitlab.gnome.org/GNOME/mutter/issues/759 > > > > > > > > While work is ongoing to fix these issues in userspace, we need to > > > > report ->possible_crtcs incorrectly for now in order to avoid > > > > introducing a regression in in userspace. Once these issues get fixed, > > > > this commit should be reverted. > > > > > > > > Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> > > > > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > --- > > > > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 11 +++++++++++ > > > > 1 file changed, 11 insertions(+) > > > > > > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > > > index b404f1ae6df7..fe8ac801d7a5 100644 > > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > > > @@ -4807,6 +4807,17 @@ static int amdgpu_dm_crtc_init(struct > > > > amdgpu_display_manager *dm, > > > > if (!acrtc->mst_encoder) > > > > goto fail; > > > > > > > > + /* > > > > + * FIXME: This is a hack to workaround the following issues: > > > > + * > > > > + * https://gitlab.gnome.org/GNOME/mutter/issues/759 > > > > + * https://gitlab.freedesktop.org/xorg/xserver/merge_requests/277 > > > > + * > > > > + * One these issues are closed, this should be removed > > > > > > Even when these issues are closed, we'll still be introducing a regression > > > if we > > > revert this change. Time for actually_possible_crtcs? :) > > > > > > You also might want to briefly explain the u/s bug in case the links go > > > sour. > > > > > > > + */ > > > > + acrtc->mst_encoder->base.possible_crtcs = > > > > + amdgpu_dm_get_encoder_crtc_mask(dm->adev); > > > > > > Why don't we put this hack in amdgpu_dm_dp_create_fake_mst_encoder()? > > > > If we don't have the same hack for i915 mst I think we shouldn't merge > > this ... broken userspace is broken. > > -Daniel > -- > Cheers, > Lyude Paul > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
