Re: [PATCH 6/7] drm/i915: use compute_page_offset() on SKL too

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 09/23/2015 06:03 PM, Chris Wilson wrote:
> On Wed, Sep 23, 2015 at 12:52:26PM -0300, Paulo Zanoni wrote:
>> The trick is not strictly necessary on SKL because the offset
>> registers allow more bits. But for FBC, doing this changes how the
>> hardware tracking works - it starts at the surface address we provide
>> - so there's a higher chance that the CRTC will be pointing to an area
>> of the frontbuffer that is actually being covered by the hardware
>> tracking mechanism. This fixes fbc-farfromfence on SKL.
>>
>> Testcase: igt/kms_frontbuffer_tracking/fbc-farfromfence
>> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_display.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 24b8a72..d40ae71 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -3031,6 +3031,7 @@ static void skylake_update_primary_plane(struct drm_crtc *crtc,
>>   	int src_x = 0, src_y = 0, src_w = 0, src_h = 0;
>>   	int dst_x = 0, dst_y = 0, dst_w = 0, dst_h = 0;
>>   	int scaler_id = -1;
>> +	int pixel_size;
>>
>>   	plane_state = to_intel_plane_state(plane->state);
>>
>> @@ -3079,6 +3080,12 @@ static void skylake_update_primary_plane(struct drm_crtc *crtc,
>>   		src_h = intel_crtc->config->pipe_src_h;
>>   	}
>>
>> +	pixel_size = drm_format_plane_cpp(fb->pixel_format, 0);
>> +	intel_crtc->dspaddr_offset = intel_gen4_compute_page_offset(dev_priv,
>> +						&x, &y, obj->tiling_mode,
>> +						pixel_size, fb->pitches[0]);
>> +	surf_addr += intel_crtc->dspaddr_offset;
>> +
>>   	if (intel_rotation_90_or_270(rotation)) {
>>   		/* stride = Surface height in tiles */
>>   		tile_height = intel_tile_height(dev, fb->pixel_format,
>
> Tvrtko mind running this past your 90/270 rotation sanity tester?

You mean igt/kms_rotation_crc ?

I don't have the background of what is this doing, but what jumps out at 
me is use of obj->tiling_mode which is not used for display tiling on 
skl+, and tile size calculations in intel_gen4_compute_page_offset seems 
to only support X tiling.

The two together would make me say that it can't possibly work. :)

Maybe Paolo can get quicker to running that igt since it sounds like he 
is already set up?

Regards,

Tvrtko
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