On Fri, Mar 14, 2014 at 05:38:55PM -0700, Ben Widawsky wrote:
> On Sat, Mar 15, 2014 at 12:08:56AM +0100, Daniel Vetter wrote:
> > Currently not an issue since we don't emit sempahores, but better
> > not forget about those.
> >
> > As a little prep work extract the ipehr decoding for cleaner control
> > flow. And apply a bit of polish.
> >
> > Cc: Ben Widawsky <ben@xxxxxxxxxxxx>
> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>
> Reviewed-by: Ben Widawsky <ben@xxxxxxxxxxxx>
>
> I've made a note to add the relevant BDW patch already.
Thanks. I'll pull it in as soon as the previous bugfix patch is reviewed
by Mika/Chris. Btw I've almost written the bdw patch myself (it's just two
lines or so + adjusting the number of dwords we scan back) but then
realized that the #defines I'm adding will needlessly conflict with your
series, so let it be.
> one comment below.
> > ---
> > drivers/gpu/drm/i915/i915_irq.c | 20 ++++++++++++++++++--
> > drivers/gpu/drm/i915/i915_reg.h | 3 ++-
> > 2 files changed, 20 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 473372a6c97d..0f3a6d791502 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -2525,6 +2525,23 @@ ring_idle(struct intel_ring_buffer *ring, u32 seqno)
> > i915_seqno_passed(seqno, ring_last_seqno(ring)));
> > }
> >
> > +static bool
> > +ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
> > +{
> > + if (INTEL_INFO(dev)->gen >= 8) {
> > + /*
> > + * FIXME: gen8 semaphore support - currently we don't emit
> > + * semaphores on bdw anyway, but this needs to be addressed when
> > + * we merge that code.
> > + */
> > + return false;
> > + } else {
>
> If you wanted to be paranoid:
> WARN_ON((ipehr & MI_SEMAPHORE_SYNC_MASK) == MI_SEMAPHORE_SYNC_INVALID)
Good idea but wrong spot. At the end of semaphore_waits_for we use the
SYNC_MASK to compute the ring pointer of the signaller. That's completely
unchecked code (and full of magic stuff). I'll throw another patch on top
to extract this and add a few paranoid checks in the spirit of your
suggestion above.
Cheers, Daniel
>
> > + ipehr &= ~MI_SEMAPHORE_SYNC_MASK;
> > + return ipehr == (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE |
> > + MI_SEMAPHORE_REGISTER);
> > + }
> > +}
> > +
> > static struct intel_ring_buffer *
> > semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
> > {
> > @@ -2533,8 +2550,7 @@ semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
> > int i;
> >
> > ipehr = I915_READ(RING_IPEHR(ring->mmio_base));
> > - if ((ipehr & ~(0x3 << 16)) !=
> > - (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE | MI_SEMAPHORE_REGISTER))
> > + if (!ipehr_is_semaphore_wait(ring->dev, ipehr))
> > return NULL;
> >
> > /*
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 146609ab42bb..23267859156f 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -244,7 +244,8 @@
> > #define MI_SEMAPHORE_SYNC_BVE (0<<16) /* VECS wait for BCS (VEBSYNC) */
> > #define MI_SEMAPHORE_SYNC_VVE (1<<16) /* VECS wait for VCS (VEVSYNC) */
> > #define MI_SEMAPHORE_SYNC_RVE (2<<16) /* VECS wait for RCS (VERSYNC) */
> > -#define MI_SEMAPHORE_SYNC_INVALID (3<<16)
> > +#define MI_SEMAPHORE_SYNC_INVALID (3<<16)
> > +#define MI_SEMAPHORE_SYNC_MASK (3<<16)
> > #define MI_SET_CONTEXT MI_INSTR(0x18, 0)
> > #define MI_MM_SPACE_GTT (1<<8)
> > #define MI_MM_SPACE_PHYSICAL (0<<8)
> > --
> > 1.8.1.4
> >
>
> --
> Ben Widawsky, Intel Open Source Technology Center
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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