On Mon, Oct 24, 2016 at 09:12:35AM +0200, Daniel Vetter wrote: > On Mon, Oct 24, 2016 at 9:00 AM, Manasi Navare > <manasi.d.navare@xxxxxxxxx> wrote: > >> I guess we just need to do some additional work on top to make sure the > >> vblank ioctl can't see invalid state. Which would then again make upfront > >> link trainig possible ... Thanks for the explanation. So the atomic_commit code in the driver calls drm_crtc_send_vblank_event(crtc, crtc->state->event);, is this what needs to be filtered to be seen by Vblank IOCTL? > > > > Could you share some more details on what work would need to be done > > for vblank? Then I can investigate it a little bit more tomor during the day. > > So the trouble is that drm_irq.c is still from the old pre-kms days. > Which means it deals in int pipe instead of struct drm_crtc *, among > other things. But we can't simply switch over because some old drivers > (pre-kms ones) still depend upon that old code. Hence we need: > > 1. Duplicate most of the code in drm_irq.c into a new > drm_crtc_vblank.c, which is only used for kms drivers. And in the > ioctl code have a DRIVER_MODESET check and either call the new kms > version (in drm_crtc_vblank.c) or the old one (still in drm_irq.c). What functions need to be duplicated? Which IOCTL are we talking about here? Do you mean in the atomic_commit_tail where we check for driver modeset, is where we should then call the new kms version of drm_crtc_send_vblank_event()? > > 2. Convert the int pipe into a drm_crtc pointer in the new kms code. > For prettiness we could (try) to do that as much as possible. > > 3. Grab the drm_crtc->mutex in the ioctl code to block these races. Again which IOCTL needs to grab the drm_crtc->mutex? What is the end goal of thsi task, what race conditions are we trying to avoid in case of these modesets during link training failures? Manasi > > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
