On Tue, Oct 13, 2015 at 12:23:38PM +0300, Ville Syrjälä wrote:
> On Sat, Oct 10, 2015 at 10:44:32AM +0100, Chris Wilson wrote:
> > We should serialise access to the intel_crtc->unpin_work through the
> > dev->event_lock spinlock. It should not be possible for it to disappear
> > without severe error as the mmio_flip worker has not tagged the
> > unpin_work pending flip-completion. Similarly if the error exists, just
> > taking the unpin_work whilst holding the spinlock and then using it
> > unserialised just masks the race. (It is supposed to be valid as the
> > unpin_work exists until the flip completion interrupt which should not
> > fire until we flush the mmio writes to update the display base which is
> > the last time we access the unpin_work from the kthread.)
> >
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=92335
> > Signed-off-by: Chris Wilson <[email protected]>
>
> So not sure what's going on yet?
>
> Patch looks OK anyway so
> Reviewed-by: Ville Syrjälä <[email protected]>
Merged to dinq since it's unclear still.
Thanks, Daniel
>
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 57
> > ++++++++++++++++++++----------------
> > 1 file changed, 32 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index cddb0c692334..71d7298648e0 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -10848,11 +10848,11 @@ void intel_prepare_page_flip(struct drm_device
> > *dev, int plane)
> > spin_unlock_irqrestore(&dev->event_lock, flags);
> > }
> >
> > -static inline void intel_mark_page_flip_active(struct intel_crtc
> > *intel_crtc)
> > +static inline void intel_mark_page_flip_active(struct intel_unpin_work
> > *work)
> > {
> > /* Ensure that the work item is consistent when activating it ... */
> > smp_wmb();
> > - atomic_set(&intel_crtc->unpin_work->pending, INTEL_FLIP_PENDING);
> > + atomic_set(&work->pending, INTEL_FLIP_PENDING);
> > /* and that it is marked active as soon as the irq could fire. */
> > smp_wmb();
> > }
> > @@ -10888,7 +10888,7 @@ static int intel_gen2_queue_flip(struct drm_device
> > *dev,
> > intel_ring_emit(ring, intel_crtc->unpin_work->gtt_offset);
> > intel_ring_emit(ring, 0); /* aux display base address, unused */
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + intel_mark_page_flip_active(intel_crtc->unpin_work);
> > return 0;
> > }
> >
> > @@ -10920,7 +10920,7 @@ static int intel_gen3_queue_flip(struct drm_device
> > *dev,
> > intel_ring_emit(ring, intel_crtc->unpin_work->gtt_offset);
> > intel_ring_emit(ring, MI_NOOP);
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + intel_mark_page_flip_active(intel_crtc->unpin_work);
> > return 0;
> > }
> >
> > @@ -10959,7 +10959,7 @@ static int intel_gen4_queue_flip(struct drm_device
> > *dev,
> > pipesrc = I915_READ(PIPESRC(intel_crtc->pipe)) & 0x0fff0fff;
> > intel_ring_emit(ring, pf | pipesrc);
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + intel_mark_page_flip_active(intel_crtc->unpin_work);
> > return 0;
> > }
> >
> > @@ -10995,7 +10995,7 @@ static int intel_gen6_queue_flip(struct drm_device
> > *dev,
> > pipesrc = I915_READ(PIPESRC(intel_crtc->pipe)) & 0x0fff0fff;
> > intel_ring_emit(ring, pf | pipesrc);
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + intel_mark_page_flip_active(intel_crtc->unpin_work);
> > return 0;
> > }
> >
> > @@ -11090,7 +11090,7 @@ static int intel_gen7_queue_flip(struct drm_device
> > *dev,
> > intel_ring_emit(ring, intel_crtc->unpin_work->gtt_offset);
> > intel_ring_emit(ring, (MI_NOOP));
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + intel_mark_page_flip_active(intel_crtc->unpin_work);
> > return 0;
> > }
> >
> > @@ -11121,7 +11121,8 @@ static bool use_mmio_flip(struct intel_engine_cs
> > *ring,
> > return ring != i915_gem_request_get_ring(obj->last_write_req);
> > }
> >
> > -static void skl_do_mmio_flip(struct intel_crtc *intel_crtc)
> > +static void skl_do_mmio_flip(struct intel_crtc *intel_crtc,
> > + struct intel_unpin_work *work)
> > {
> > struct drm_device *dev = intel_crtc->base.dev;
> > struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -11162,11 +11163,12 @@ static void skl_do_mmio_flip(struct intel_crtc
> > *intel_crtc)
> > I915_WRITE(PLANE_CTL(pipe, 0), ctl);
> > I915_WRITE(PLANE_STRIDE(pipe, 0), stride);
> >
> > - I915_WRITE(PLANE_SURF(pipe, 0), intel_crtc->unpin_work->gtt_offset);
> > + I915_WRITE(PLANE_SURF(pipe, 0), work->gtt_offset);
> > POSTING_READ(PLANE_SURF(pipe, 0));
> > }
> >
> > -static void ilk_do_mmio_flip(struct intel_crtc *intel_crtc)
> > +static void ilk_do_mmio_flip(struct intel_crtc *intel_crtc,
> > + struct intel_unpin_work *work)
> > {
> > struct drm_device *dev = intel_crtc->base.dev;
> > struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -11186,31 +11188,36 @@ static void ilk_do_mmio_flip(struct intel_crtc
> > *intel_crtc)
> >
> > I915_WRITE(reg, dspcntr);
> >
> > - I915_WRITE(DSPSURF(intel_crtc->plane),
> > - intel_crtc->unpin_work->gtt_offset);
> > + I915_WRITE(DSPSURF(intel_crtc->plane), work->gtt_offset);
> > POSTING_READ(DSPSURF(intel_crtc->plane));
> > -
> > }
> >
> > /*
> > * XXX: This is the temporary way to update the plane registers until we
> > get
> > * around to using the usual plane update functions for MMIO flips
> > */
> > -static void intel_do_mmio_flip(struct intel_crtc *intel_crtc)
> > +static void intel_do_mmio_flip(struct intel_mmio_flip *mmio_flip)
> > {
> > - struct drm_device *dev = intel_crtc->base.dev;
> > + struct intel_crtc *crtc = mmio_flip->crtc;
> > + struct intel_unpin_work *work;
> >
> > - intel_mark_page_flip_active(intel_crtc);
> > + spin_lock_irq(&crtc->base.dev->event_lock);
> > + work = crtc->unpin_work;
> > + spin_unlock_irq(&crtc->base.dev->event_lock);
> > + if (work == NULL)
> > + return;
> >
> > - intel_pipe_update_start(intel_crtc);
> > + intel_mark_page_flip_active(work);
> >
> > - if (INTEL_INFO(dev)->gen >= 9)
> > - skl_do_mmio_flip(intel_crtc);
> > + intel_pipe_update_start(crtc);
> > +
> > + if (INTEL_INFO(mmio_flip->i915)->gen >= 9)
> > + skl_do_mmio_flip(crtc, work);
> > else
> > /* use_mmio_flip() retricts MMIO flips to ilk+ */
> > - ilk_do_mmio_flip(intel_crtc);
> > + ilk_do_mmio_flip(crtc, work);
> >
> > - intel_pipe_update_end(intel_crtc);
> > + intel_pipe_update_end(crtc);
> > }
> >
> > static void intel_mmio_flip_work_func(struct work_struct *work)
> > @@ -11218,15 +11225,15 @@ static void intel_mmio_flip_work_func(struct
> > work_struct *work)
> > struct intel_mmio_flip *mmio_flip =
> > container_of(work, struct intel_mmio_flip, work);
> >
> > - if (mmio_flip->req)
> > + if (mmio_flip->req) {
> > WARN_ON(__i915_wait_request(mmio_flip->req,
> > mmio_flip->crtc->reset_counter,
> > false, NULL,
> > &mmio_flip->i915->rps.mmioflips));
> > + i915_gem_request_unreference__unlocked(mmio_flip->req);
> > + }
> >
> > - intel_do_mmio_flip(mmio_flip->crtc);
> > -
> > - i915_gem_request_unreference__unlocked(mmio_flip->req);
> > + intel_do_mmio_flip(mmio_flip);
> > kfree(mmio_flip);
> > }
> >
> > --
> > 2.6.1
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > [email protected]
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> [email protected]
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
[email protected]
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
