[Intel-gfx] [PATCH 3/4] drm/i915: Support NV12 in rotated GGTT mapping

[Tvrtko Ursulin]

On 09/24/2015 05:35 PM, Ville Syrjälä wrote:
> On Mon, Sep 21, 2015 at 10:45:34AM +0100, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> Just adding the rotated UV plane at the end of the rotated Y plane.
>>
>> v2: Rebase.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_gem_gtt.c  | 37 ++++++++++++++++++++++++++++++------
>>   drivers/gpu/drm/i915/i915_gem_gtt.h  |  3 +++
>>   drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
>>   3 files changed, 46 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> index 59c934fb9230..2df9d16dcefd 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> @@ -3272,10 +3272,13 @@ intel_rotate_fb_obj_pages(struct i915_ggtt_view *ggtt_view,
>>   {
>>   	struct intel_rotation_info *rot_info = &ggtt_view->rotation_info;
>>   	unsigned int size_pages = rot_info->size >> PAGE_SHIFT;
>> +	unsigned int size_pages_uv;
>>   	struct sg_page_iter sg_iter;
>>   	unsigned long i;
>>   	dma_addr_t *page_addr_list;
>>   	struct sg_table *st;
>> +	unsigned int uv_start_page;
>> +	struct scatterlist *sg;
>>   	int ret = -ENOMEM;
>>
>>   	/* Allocate a temporary list of source pages for random access. */
>> @@ -3284,12 +3287,18 @@ intel_rotate_fb_obj_pages(struct i915_ggtt_view *ggtt_view,
>>   	if (!page_addr_list)
>>   		return ERR_PTR(ret);
>>
>> +	/* Account for UV plane with NV12. */
>> +	if (rot_info->pixel_format == DRM_FORMAT_NV12)
>> +		size_pages_uv = rot_info->size_uv >> PAGE_SHIFT;
>> +	else
>> +		size_pages_uv = 0;
>> +
>>   	/* Allocate target SG list. */
>>   	st = kmalloc(sizeof(*st), GFP_KERNEL);
>>   	if (!st)
>>   		goto err_st_alloc;
>>
>> -	ret = sg_alloc_table(st, size_pages, GFP_KERNEL);
>> +	ret = sg_alloc_table(st, size_pages + size_pages_uv, GFP_KERNEL);
>>   	if (ret)
>>   		goto err_sg_alloc;
>>
>> @@ -3301,15 +3310,30 @@ intel_rotate_fb_obj_pages(struct i915_ggtt_view *ggtt_view,
>>   	}
>>
>>   	/* Rotate the pages. */
>> -	rotate_pages(page_addr_list, 0,
>> +	sg = rotate_pages(page_addr_list, 0,
>>   		     rot_info->width_pages, rot_info->height_pages,
>>   		     st, NULL);
>>
>> +	/* Append the UV plane if NV12. */
>> +	if (rot_info->pixel_format == DRM_FORMAT_NV12) {
>> +		uv_start_page = size_pages;
>> +
>> +		/* Check for tile-row un-alignment. */
>> +		if (offset_in_page(rot_info->uv_offset))
>> +			uv_start_page--;
>> +
>> +		rotate_pages(page_addr_list, uv_start_page,
>> +			     rot_info->width_pages_uv,
>> +			     rot_info->height_pages_uv,
>> +			     st, sg);
>> +	}
>> +
>>   	DRM_DEBUG_KMS(
>> -		      "Created rotated page mapping for object size %zu (pitch=%u, height=%u, pixel_format=0x%x, %ux%u tiles, %u pages).\n",
>> +		      "Created rotated page mapping for object size %zu (pitch=%u, height=%u, pixel_format=0x%x, %ux%u tiles, %u pages (%u plane 0)).\n",
>>   		      obj->base.size, rot_info->pitch, rot_info->height,
>>   		      rot_info->pixel_format, rot_info->width_pages,
>> -		      rot_info->height_pages, size_pages);
>> +		      rot_info->height_pages, size_pages + size_pages_uv,
>> +		      size_pages);
>>
>>   	drm_free_large(page_addr_list);
>>
>> @@ -3321,10 +3345,11 @@ err_st_alloc:
>>   	drm_free_large(page_addr_list);
>>
>>   	DRM_DEBUG_KMS(
>> -		      "Failed to create rotated mapping for object size %zu! (%d) (pitch=%u, height=%u, pixel_format=0x%x, %ux%u tiles, %u pages)\n",
>> +		      "Failed to create rotated mapping for object size %zu! (%d) (pitch=%u, height=%u, pixel_format=0x%x, %ux%u tiles, %u pages (%u plane 0))\n",
>>   		      obj->base.size, ret, rot_info->pitch, rot_info->height,
>>   		      rot_info->pixel_format, rot_info->width_pages,
>> -		      rot_info->height_pages, size_pages);
>> +		      rot_info->height_pages, size_pages + size_pages_uv,
>> +		      size_pages);
>>   	return ERR_PTR(ret);
>>   }
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
>> index 82750073d5b3..197183d5c543 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
>> @@ -138,10 +138,13 @@ enum i915_ggtt_view_type {
>>   struct intel_rotation_info {
>>   	unsigned int height;
>>   	unsigned int pitch;
>> +	unsigned int uv_offset;
>>   	uint32_t pixel_format;
>>   	uint64_t fb_modifier;
>>   	unsigned int width_pages, height_pages;
>>   	uint64_t size;
>> +	unsigned int width_pages_uv, height_pages_uv;
>> +	uint64_t size_uv;
>>   };
>>
>>   struct i915_ggtt_view {
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index e19b8e699c00..2db7cc42539c 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -2263,6 +2263,7 @@ intel_fill_fb_ggtt_view(struct i915_ggtt_view *view, struct drm_framebuffer *fb,
>>   	info->height = fb->height;
>>   	info->pixel_format = fb->pixel_format;
>>   	info->pitch = fb->pitches[0];
>> +	info->uv_offset = fb->offsets[1];
>
> OK, so this already came up a bit when I was looking at Chandra's stuff,
> but we really have to define what fb->offsets[] means now.
>
> On one hand, it would be very logical for it to be a raw byte offset
> into the object where the fb starts. But on the other hand that perhaps
> makes it a bit more difficult for userspace to compute offsets[1] for
> the CbCr plane. Also we have fences to consider, and currently we even
> require that the fence stride matches the fb stride, even though that
> may not really be necessary. So maybe it should be the linear offset
> instead.
>
> So which way should we go?

No idea, I'm afraid I don't have the wide enough knowledge on this one 
to contribute hugely.

Why would it be difficult for userspace to compute a byte offset to the 
UV plane though? Presumably it had to know it already to have rendered 
anything - otherwise why and how would it be giving this frame buffer to 
the kernel?

Regards,

Tvrtko