Re: [PATCH 2/2] drm/i915: frontbuffer invalidate at flip schedule

[Ramalingam C <ramalingam.c@intel.com>]

True.

Chris and Vivi,

I am trying to understand the PSR exit and entry along with SFU 
requirement here.
AFAIK in existing code also
         on rendering start fb_obj_invalidate is calling the 
psr_invalidate(psr_exit)
         on flip prepare single frame update is done
         on flip complete frontbuffer_invalidate is calling 
psr_flush(psr_reenable)
         on rendering complete fb_obj_flush is calling the 
psr_flush(psr_reenable)

On Every rendering start if we exit the PSR, then there is no advantage 
of setting SFU at flip prepare.
Please correct me if I am wrong.

On Thursday 11 June 2015 03:26 PM, Chris Wilson wrote:
> On Thu, Jun 11, 2015 at 03:08:35PM +0530, Ramalingam C wrote:
>> After scheduling a flip for obj, frontbuffer should be invalidated.
>> Hence intel_frontbuffer_invalidate is invoked at flip preparation.
>>
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=90418
>> ---
>>   drivers/gpu/drm/i915/intel_frontbuffer.c |    1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_frontbuffer.c b/drivers/gpu/drm/i915/intel_frontbuffer.c
>> index 4cea589..07147a7 100644
>> --- a/drivers/gpu/drm/i915/intel_frontbuffer.c
>> +++ b/drivers/gpu/drm/i915/intel_frontbuffer.c
>> @@ -268,6 +268,7 @@ void intel_frontbuffer_flip_prepare(struct drm_device *dev,
>>   	dev_priv->fb_tracking.busy_bits &= ~frontbuffer_bits;
>>   	mutex_unlock(&dev_priv->fb_tracking.lock);
>>   
>> +	intel_frontbuffer_invalidate(dev, NULL, ORIGIN_FLIP, frontbuffer_bits);
>>   	intel_psr_single_frame_update(dev);
> This then has the side effect of calling psr_invalidate (psr_exit)
> followed by the single-shot psr update, which doesn't seem desirable.
> -Chris
>

-- 
Thanks,
--Ram

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