Re: [Intel-gfx] Linux 3.16-rc2

From: Jiri Kosina
Date: Tue Jul 08 2014 - 08:47:05 EST


On Tue, 8 Jul 2014, Chris Wilson wrote:

> > I actually tried to introduce rather large delays between individual
> > I915_WRITE() calls in the ring initialization sequence a couple weeks ago
> > already, but it resulted in complete machine lockup (which is worse than
> > my usual symptoms) during resume. Therefore I probably lack the knowledge
> > of internal workings of the HW that would allow me to guess what the
> > reasonable timeout value should be.
> >
> > Willing to test any patches.
>
> Are you using the extra patches on bug 76554? If not, try

Just for debugging.

> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index e18ed05dc0d5..48326f9628d4 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -526,6 +526,9 @@ static int init_ring_common(struct intel_engine_cs *ring)
> ((ringbuf->size - PAGE_SIZE) & RING_NR_PAGES)
> | RING_VALID);
>
> + I915_WRITE_HEAD(ring, 0);
> + (void)I915_READ_HEAD(ring);
> +
> /* If the head is still not zero, the ring is dead */
> if (wait_for((I915_READ_CTL(ring) & RING_VALID) != 0 &&
> I915_READ_START(ring) == i915_gem_obj_ggtt_offset(obj) &&

Tried on top of current Linus' tree, and no improvement. ring
initialization failure upon resume, and window redrawing hosed.

--
Jiri Kosina
SUSE Labs
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