On Wed, Jun 03, 2020 at 02:13:43PM +0300, Ville Syrjälä wrote: > On Wed, Jun 03, 2020 at 10:45:23AM +0000, Simon Ser wrote: > > In update_output_state, the link-status property was reset to GOOD to > > ensure legacy drmModeSetCrtc re-trains the link. However this auto-reset > > is also performed on an atomic commit without ALLLOW_MODESET. If a > > I didn't think udate_output_state() was getting called for > non-legacy paths. Where is that coming from?
Oops, I'm blind and you're right, there's no bug. We already only force-set this for legacy modeset (and fbcon). That also means that atomic userspace has to handle this, which is maybe not so awesome ... So maybe we need to duct-tape over this for atomic too, and in that case it should be only done when ALLOW_MODESET is set. But maybe all the compositors that care will handle this :-/ -Daniel > > > driver reads link-status to figure out whether to re-train the link, > > this could cause an atomic commit failure. User-space doesn't expect > > such a failure, because commits without ALLOW_MODESET aren't supposed to > > fail because of link training issues. > > > > Change update_output_state to implicitly reset link-status to GOOD only > > if ALLOW_MODESET is set. This is the case for legacy drmModeSetCrtc > > because drm_atomic_state_init sets it (and is used in > > drm_atomic_helper_set_config, called from drm_mode_setcrtc). > > > > Drivers don't seem to read link-status at the moment -- they seem to > > rely on user-space performing a modeset instead. So this shouldn't > > result in any change in behaviour, this should only prevent future > > failures if drivers start reading link-status. > > > > Signed-off-by: Simon Ser <cont...@emersion.fr> > > Suggested-by: Pekka Paalanen <ppaala...@gmail.com> > > Cc: Daniel Vetter <dan...@ffwll.ch> > > Cc: Manasi Navare <manasi.d.nav...@intel.com> > > --- > > drivers/gpu/drm/drm_atomic.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > > index 965173fd0ac2..3d9d9e6f7397 100644 > > --- a/drivers/gpu/drm/drm_atomic.c > > +++ b/drivers/gpu/drm/drm_atomic.c > > @@ -1426,7 +1426,8 @@ static int update_output_state(struct > > drm_atomic_state *state, > > return ret; > > > > /* Make sure legacy setCrtc always re-trains */ > > - new_conn_state->link_status = DRM_LINK_STATUS_GOOD; > > + if (state->allow_modeset) > > + new_conn_state->link_status = > > DRM_LINK_STATUS_GOOD; > > } > > } > > > > -- > > 2.26.2 > > > > > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
