[Mesa-dev] [PATCH 1/6] st/dri: allow to create image for formats that only support SV or RT binding

[Eric Anholt]

Michel Dänzer <michel at daenzer.net> writes:

> On 2019-04-12 7:33 p.m., Lucas Stach wrote:
>> Unconditionally requesting both bindings can lead to premature
>> failure to create a valid image.
>> 
>> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
>> ---
>>  src/gallium/state_trackers/dri/dri2.c | 13 +++++++++++--
>>  1 file changed, 11 insertions(+), 2 deletions(-)
>> 
>> diff --git a/src/gallium/state_trackers/dri/dri2.c b/src/gallium/state_trackers/dri/dri2.c
>> index efb43c0d7973..510b7f8d04a7 100644
>> --- a/src/gallium/state_trackers/dri/dri2.c
>> +++ b/src/gallium/state_trackers/dri/dri2.c
>> @@ -987,14 +987,23 @@ dri2_create_image_common(__DRIscreen *_screen,
>>  {
>>     const struct dri2_format_mapping *map = dri2_get_mapping_by_format(format);
>>     struct dri_screen *screen = dri_screen(_screen);
>> +   struct pipe_screen *pscreen = screen->base.screen;
>>     __DRIimage *img;
>>     struct pipe_resource templ;
>> -   unsigned tex_usage;
>> +   unsigned tex_usage = 0;
>>  
>>     if (!map)
>>        return NULL;
>>  
>> -   tex_usage = PIPE_BIND_RENDER_TARGET | PIPE_BIND_SAMPLER_VIEW;
>> +   if (pscreen->is_format_supported(pscreen, map->pipe_format, screen->target,
>> +                                    0, 0, PIPE_BIND_RENDER_TARGET))
>> +      tex_usage |= PIPE_BIND_RENDER_TARGET;
>> +   if (pscreen->is_format_supported(pscreen, map->pipe_format, screen->target,
>> +                                    0, 0, PIPE_BIND_SAMPLER_VIEW))
>> +      tex_usage |= PIPE_BIND_SAMPLER_VIEW;
>> +
>> +   if (!tex_usage)
>> +      return NULL;
>>  
>>     if (use & __DRI_IMAGE_USE_SCANOUT)
>>        tex_usage |= PIPE_BIND_SCANOUT;
>> 
>
> Since there are no __DRI_IMAGE_USE_* flags for rendering & sampling, the
> expectation does seem to be that both are supported. What happens if an
> image is created for a format which only supports sampling, then the
> caller attempts rendering to it?

From OES_EGL_image.txt:

    If the GL is unable to specify a texture object using the supplied
    eglImageOES <image> (if, for example, <image> refers to a multisampled
    eglImageOES), the error INVALID_OPERATION is generated.

...

    If the GL is unable to create a renderbuffer using the specified
    eglImageOES, the error INVALID_OPERATION is generated.  If <image>
    does not refer to a valid eglImageOES object, the error
    INVALID_VALUE is generated.

and st_cb_eglimage.c is checking the screen for sampler / rendertarget
support for the images that it looks up.
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