[Mesa-dev] [PATCH 0/2] wrong fourcc was returned for imported images

[James Xiong]

On Thu, 5 Apr 2018 15:05:26 +0300
Tapani Pälli <tapani.palli at intel.com> wrote:

> Hi;
> 
> On 04/05/2018 02:51 AM, James Xiong wrote:
> > From: "Xiong, James" <james.xiong at intel.com>
> > 
> > The importer creates an image out of the imported FOURCC_NV12
> > texture, the image's dri_format is set to R8(same as the first
> > plane's format), when it queries the image's fourcc, mesa goes
> > through intel_image_format table and returns FOURCC_R8.  
> 
> Could you explain the use case a bit, I'm not sure I understand how
> this happens. First someone imports dmabufs, creating EGLImage. Then
> a texture is associated with that (glEGLImageTargetTexture2DOES?), is
> it so that then we create yet another EGLImage from that texture or
> am I completely lost here? :)
> 
Sorry for the confusion. 

What actually happened was the exporter 1) calls eglCreateImageKHR()
to create an image from a NV12 texture, 2) calls
eglExportDMABUFImageQueryMESA() but the fourcc_r8 is returned instead
of fourcc_nv12.

Essentially, image->dri_format is the first plane's format, i.e.
__DRI_IMAGE_FORMAT_R8 in our case, when querying fourcc,
intel_lookup_fourcc() gets the following entry from the table
intel_image_formats:
   { __DRI_IMAGE_FOURCC_R8, __DRI_IMAGE_COMPONENTS_R, 1,
     { { 0, 0, 0, __DRI_IMAGE_FORMAT_R8, 1 }, } },
instead of the corret one:
   { __DRI_IMAGE_FOURCC_NV12, __DRI_IMAGE_COMPONENTS_Y_UV, 2,
     { { 0, 0, 0, __DRI_IMAGE_FORMAT_R8, 1 },
       { 1, 1, 1, __DRI_IMAGE_FORMAT_GR88, 2 } } },

To fix this, the image should inherit the texture's planar_format which
contains the original fourcc; When the user application queries the
fourcc, we can return the saved fourcc if planar_format is NULL;
otherwise fallback to the original way to look up the fourcc.

> > The solution is to 1) set the image's planar_format using the
> > texture's in function intel_create_image_from_texture(). 2) when
> > queried, return the saved fourcc at planar_format
> > 
> > Xiong, James (2):
> >    i965: init image's planar_format in
> > intel_create_image_from_texture i965: return the fourcc saved in
> > __DRIimage
> > 
> >   src/mesa/drivers/dri/i965/intel_screen.c | 16 +++++++++++++---
> >   1 file changed, 13 insertions(+), 3 deletions(-)
> >