[Intel-gfx] [PATCH] drm/i915: Handle YUV subpixel support better

[Maarten Lankhorst]

Op 18-03-2019 om 19:15 schreef Ville Syrjälä:
> On Mon, Mar 18, 2019 at 04:13:57PM +0100, Maarten Lankhorst wrote:
>> Op 18-03-2019 om 15:18 schreef Ville Syrjälä:
>>> On Mon, Mar 18, 2019 at 03:07:18PM +0100, Maarten Lankhorst wrote:
>>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>>> ---
>>>>  drivers/gpu/drm/i915/intel_sprite.c | 29 +++++++++++++++++++----------
>>>>  1 file changed, 19 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
>>>> index 268fb34ff0e2..862fc172042f 100644
>>>> --- a/drivers/gpu/drm/i915/intel_sprite.c
>>>> +++ b/drivers/gpu/drm/i915/intel_sprite.c
>>>> @@ -269,7 +269,8 @@ int intel_plane_check_src_coordinates(struct intel_plane_state *plane_state)
>>>>  {
>>>>  	const struct drm_framebuffer *fb = plane_state->base.fb;
>>>>  	struct drm_rect *src = &plane_state->base.src;
>>>> -	u32 src_x, src_y, src_w, src_h;
>>>> +	u32 src_x, src_y, src_w, src_h, hsub, vsub;
>>>> +	bool rotated = drm_rotation_90_or_270(plane_state->base.rotation);
>>>>  
>>>>  	/*
>>>>  	 * Hardware doesn't handle subpixel coordinates.
>>>> @@ -287,18 +288,26 @@ int intel_plane_check_src_coordinates(struct intel_plane_state *plane_state)
>>>>  	src->y1 = src_y << 16;
>>>>  	src->y2 = (src_y + src_h) << 16;
>>>>  
>>>> -	if (fb->format->is_yuv &&
>>>> -	    (src_x & 1 || src_w & 1)) {
>>>> -		DRM_DEBUG_KMS("src x/w (%u, %u) must be a multiple of 2 for YUV planes\n",
>>>> -			      src_x, src_w);
>>>> +	if (!fb->format->is_yuv)
>>>> +		return 0;
>>>> +
>>>> +	/* YUV specific checks */
>>>> +	if (!rotated) {
>>>> +		hsub = fb->format->hsub;
>>>> +		vsub = fb->format->vsub;
>>>> +	} else {
>>>> +		hsub = vsub = max(fb->format->hsub, fb->format->vsub);
>>> Why this? From the looks of things there should be no need to deal with
>>> rotation in this function at all.
>> I wrote a dumb test that fails if I rotate YUYV.
>>
>> https://patchwork.freedesktop.org/patch/286170/
>>
>> Corrupted image:
>>
>> (kms_yuv:1155) igt_kms-DEBUG: display: A.0: plane_set_rotation(90°)
>> (kms_yuv:1155) igt_kms-DEBUG: display: A.0: src_set_position(18,33)
>> (kms_yuv:1155) igt_kms-DEBUG: display: A.0: src_set_size(44x65)
>> (kms_yuv:1155) igt_kms-DEBUG: display: A.0: plane_set_position(64,64)
>> (kms_yuv:1155) igt_kms-DEBUG: display: A.0: plane_set_size (256x256)
>>
>> I had a 80x128 fb, only showing the center part which should be white, with a black border around it to cause CRC errors if we mess up clipping.
>>
>> The scaling works fine, but the clipping does not in this case. I am getting a corrupted plane on screen which is mostly white, but with black dots in each tile.
>>
>> Scaling just magnifies this corruption. :)
> Hmm. I just poked my KBL a bit and it is also showing curious
> behaviour. Even with 90/270 rotation it is in fact the TILEOFF
> X coordinate that needs to be even (actually the hw just appears
> to ignore the lsb). I can make the Y coordinate odd, and the image
> still looks correct to my eyes. So feels like someone forgot to
> to remove a (x&~1) from the hw when they added the 90/270 rotation,
> and yet they went to the trouble of making odd Y coordinates work
> correctly. Quite stange.
>
> Width/height being odd seems to handled just fine by the hw.
>
Hmm does that mean we should keep the original checks in place while checking format->h/vsub, and on top reject the unrotated Y coordinate being a multiple of hsub when rotating?

~Maarten