On Wed, Jan 27, 2016 at 03:43:49PM +0000, daniele.ceraolospurio@xxxxxxxxx wrote:
> From: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
>
> While running some tests on the scheduler patches with rpm enabled I
> came across a corruption in the ringbuffer, which was root-caused to
> the GPU being suspended while commands were being emitted to the
> ringbuffer. The access to memory was failing because the GPU needs to
> be awake when accessing stolen memory (where my ringbuffer was located).
> Since we have this constraint it looks like a sensible idea to check
> that we hold a refcount when we access the rungbuffer.
>
> v2: move the check from ring_begin to ringbuffer iomap time (Chris)
> v3: update comment (Chris)
>
> Cc: John Harrison <John.C.Harrison@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 6f5b511..133321a 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -2119,6 +2119,9 @@ int intel_pin_and_map_ringbuffer_obj(struct drm_device *dev,
> return ret;
> }
>
> + /* Access through the GTT requires the device to be awake. */
> + assert_rpm_wakelock_held(dev_priv);
> +
Hmm. This function doesn't actually acces the ring buffer, so it's a bit
odd to see this here.
> ringbuf->virtual_start = ioremap_wc(dev_priv->gtt.mappable_base +
> i915_gem_obj_ggtt_offset(obj), ringbuf->size);
> if (ringbuf->virtual_start == NULL) {
> --
> 1.9.1
>
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--
Ville Syrjälä
Intel OTC
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