On Thu, Jul 31, 2014 at 08:59:08PM +1000, Dave Airlie wrote: > On 31 July 2014 17:37, Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Thu, Jul 31, 2014 at 1:49 AM, Dave Airlie <airlied@xxxxxxxxx> wrote: > >> Daniel, the only way intel_dp->is_mst can get reset is inside this path. > > > > Ok, so that one should be safe. Then I guess we can just push the > > locking down into the respective non-mst leafs (since atm we do > > link-retraining without any locking, which isn't good). And it needs > > to be dev->mode_config.mutex, not connection mutex. Why that? We can't be doing a modeset w/o connection_mutex so that seems like it should be enough. Well, there's also dpms which leaves the crtc<->encoder<->connector links intact but that too takes connection_mutex currently. > > I'd like to know why we do link training at this point though as well, > adding locking is required of course, I was just going to wrap the > short irq call to the link status check with the lock, but I think it > should be possible to push it down further, I don't really know why the sink generates the hpd when we turn off the port, but that doesn't really matter I think. We need to be prepared for hpds at any time. intel_dp_check_link_status() just checks if there's a crtc, which there is (either the old one or the new one, depending on how far along the modeset path we are I guess), and then it just checks drm_dp_channel_eq_ok() which says false since the link was turned off, and then it proceeds to retrain the link. Maybe it should also check crtc->active? Though that itself won't eliminate the problem unless the locking gets fixed somehow. > > I'm not sure how vague the spec is on what should happen on HPDs, but > if we drop the port clock we obviously will lose the link, but we > should also know not to be retraining it at that point anyways. > > Dave. -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx