Re: [PATCH] drm/i915: Perform an invalidate prior to executing golden renderstate

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Mika Kuoppala <mika.kuoppala@linux.intel.com> writes:

> Mika Kuoppala <mika.kuoppala@linux.intel.com> writes:
>
>> Chris Wilson <chris@chris-wilson.co.uk> 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@chris-wilson.co.uk>
>>> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
>>> Cc: stable@vger.kernel.org
>>
>> 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@intel.com>
>
> On hindsight, should we actually do the flush through add request?

No, as it is not there anymore in gem_init_hw. -ETOOMUCHCOFFEE.

> -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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