Re: [PATCH] drm/i915: Make sure DC writes are coherent on flush.

From: Francisco Jerez <currojerez@riseup.net>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	intel-gfx@lists.freedesktop.org
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH] drm/i915: Make sure DC writes are coherent on	flush.
Date: Thu, 14 Jan 2016 09:16:04 -0800	[thread overview]
Message-ID: <87ziw8dquj.fsf@riseup.net> (raw)
In-Reply-To: <87h9igxxgz.fsf@intel.com>

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Jani Nikula <jani.nikula@linux.intel.com> writes:

> On Thu, 14 Jan 2016, Francisco Jerez <currojerez@riseup.net> wrote:
>> We need to set the DC FLUSH PIPE_CONTROL bit on Gen7+ to guarantee
>> that writes performed via the HDC are visible in memory.  Fixes an
>> intermittent failure in a Piglit test that writes to a BO from a
>> shader using GL atomic counters (implemented as HDC untyped atomics)
>> and then expects the memory to read back the same value after mapping
>> it on the CPU.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91298
>> Tested-by: Mark Janes <mark.a.janes@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>
> Francisco, this is missing your Signed-off-by i.e. developer certificate
> of origin http://developercertificate.org/ - can't push without. Please
> reply with that.
>
Oops, sorry for that -- And yeah it shouldn't hurt to CC stable too.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>

> BR,
> Jani.
>
>
>> ---
>>  drivers/gpu/drm/i915/intel_lrc.c        | 1 +
>>  drivers/gpu/drm/i915/intel_ringbuffer.c | 2 ++
>>  2 files changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
>> index ab344e0..02213c6 100644
>> --- a/drivers/gpu/drm/i915/intel_lrc.c
>> +++ b/drivers/gpu/drm/i915/intel_lrc.c
>> @@ -1735,6 +1735,7 @@ static int gen8_emit_flush_render(struct drm_i915_gem_request *request,
>>  	if (flush_domains) {
>>  		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
>>  		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
>> +		flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
>>  		flags |= PIPE_CONTROL_FLUSH_ENABLE;
>>  	}
>>  
>> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> index 4060acf..8cd8aab 100644
>> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> @@ -331,6 +331,7 @@ gen7_render_ring_flush(struct drm_i915_gem_request *req,
>>  	if (flush_domains) {
>>  		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
>>  		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
>> +		flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
>>  		flags |= PIPE_CONTROL_FLUSH_ENABLE;
>>  	}
>>  	if (invalidate_domains) {
>> @@ -403,6 +404,7 @@ gen8_render_ring_flush(struct drm_i915_gem_request *req,
>>  	if (flush_domains) {
>>  		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
>>  		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
>> +		flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
>>  		flags |= PIPE_CONTROL_FLUSH_ENABLE;
>>  	}
>>  	if (invalidate_domains) {
>
> -- 
> Jani Nikula, Intel Open Source Technology Center

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