Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> writes:
> Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
>
>> As we may have just bound the renderstate into the GGTT for execution, we
>> need to ensure that the GTT TLB are also flushed.
>>
>> On snb-gt2, this would cause a random GPU hang at the start of a new
>> context (e.g. boot) and on snb-gt1, it was causing the renderstate batch
>> to take ~10s. It was the GPU hang that revealed the truth, as the CS
>> gleefully executed beyond the end of the golden renderstate batch, a good
>> indicator for a GTT TLB miss.
>>
>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
>
> The flush has been there but got stomped by:
>
> Fixes: dc4be6071a24 ("drm/i915: Add explicit request management to i915_gem_init_hw()")
>
> Now we can fix the gen6 renderstate too ;)
>
> Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
On hindsight, should we actually do the flush through add request?
-Mika
>
>> ---
>> drivers/gpu/drm/i915/i915_gem_render_state.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_render_state.c b/drivers/gpu/drm/i915/i915_gem_render_state.c
>> index 241d827b85fb..3703dc91eeda 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_render_state.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_render_state.c
>> @@ -242,6 +242,10 @@ int i915_gem_render_state_emit(struct drm_i915_gem_request *req)
>> goto err_unpin;
>> }
>>
>> + ret = req->engine->emit_flush(req, EMIT_INVALIDATE);
>> + if (ret)
>> + goto err_unpin;
>> +
>> ret = req->engine->emit_bb_start(req,
>> so->batch_offset, so->batch_size,
>> I915_DISPATCH_SECURE);
>> --
>> 2.13.3
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