On Fri, Feb 21, 2020 at 06:16:57PM +0100, Daniel Vetter wrote: > On Fri, Feb 21, 2020 at 06:09:04PM +0200, Ville Syrjälä wrote: > > On Fri, Feb 21, 2020 at 05:40:31PM +0200, Ville Syrjälä wrote: > > > On Fri, Feb 21, 2020 at 03:42:56PM +0100, Daniel Vetter wrote: > > > > On Fri, Feb 21, 2020 at 12:43 PM Ville Syrjälä > > > > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > On Fri, Feb 21, 2020 at 01:32:29PM +0200, Jani Nikula wrote: > > > > > > On Thu, 20 Feb 2020, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > Looks like getting rid of private_flags is going to be pretty > > > > > > > straightforward. I'll post patches for that once this first series > > > > > > > lands. > > > > > > > > > > > > Going all in on crtc state? I suppose migrating away from private_flags > > > > > > could easily start in i915 before that. Seems rather independent. > > > > > > > > > > > > I guess it's __intel_get_crtc_scanline() and: > > > > > > > > > > > > vblank = &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)]; > > > > > > mode = &vblank->hwmode; > > > > > > > > > > > > if (mode->private_flags & I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP) > > > > > > > > > > > > that gives me the creeps in reviewing all that. > > > > > > > > > > > > There's also [1] adding new uses for private_flags; I think there were > > > > > > issues in getting at the right crtc state on some of those paths, but I > > > > > > forget the exact details. Ideas? > > > > > > > > > > I'm just going to move them to the crtc_state and put a copy into the > > > > > crtc itself for the vblank code. Pretty much a 1:1 replacement. > > > > > Saves me from having to think ;) > > > > > > > > I've looked through the patches, and didn't spot any place where we > > > > couldn't just get at the full crtc state. Might need some crtc->state > > > > dereferencing and upcasting and making sure stuff is ordered correctly > > > > with enable/disable paths of crtc, but nothing to jump over. > > > > > > swap_state() could easily race with the irq handler. I guess > > > practically unlikely the old crtc state would disappear before > > > the irq handler is done, but still seems somewhat dubious. > > > > And I guess the bigger problem is that swap_state() happens way too > > early. So crtc->state would be pointing to bogus stuff while we're > > disabling the crtc. > > Uh, so we're essentially piggy-packing some random i915 state on top of > the hw timing stuff the vblank handler does, and hope that this is > race-free enough to not matter? > > I think the right solution there would be to have a proper > spinlock_irqsafe for this stuff that the dsi TE handler needs, and through > that make sure that we're actually not going boom. At least it looked like > there's also irq handling bits outside of the vblank code, so the vblank > locking is not going to safe the day. I haven't actually looked at the DSI TE stuff so far, so no idea what's going on there. -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
