[Mesa-dev] [PATCH] anv: GetDeviceImageFormatProperties: fix transfer destination formats

[Jason Ekstrand]

On Aug 3, 2016 5:53 AM, "Lionel Landwerlin" <lionel.g.landwerlin at intel.com>
wrote:
>
> We let the user believe we support some transfer destination formats
> which we don't. This can lead to crashes when actually trying to use
> those formats for example on
> dEQP-VK.api.copy_and_blit.image_to_image.* tests.
>
> Allow formats we can render to as meta implements transfers using
> attachments.

Sadly, it's not quite that simple... Nanley and I had a long chat about
this in the office last week.  I'll try and summarize here.  Let's take one
particular format as an example: R9G9B9E5.  This format is required to be
supported for sampling with VK_TILING_OPTIMAL but has no requirements on
rendering.  We can sample from it but cannot render to it.  Since it's
required to be supported in a tilled configuration, the only way the user
can get data into it is through vkCopy* commands. This means it has to be
supported as a transfer destination.  This means we have to support
vkClearColorImage on it as well.

This implies two things: First, the correct criterion for supporting
transfer operations is render, depth-stencil, *or* sampling.  Second, we
really need to come up with a better clearing sorry than just "bind as a
render target and draw".  While this works for most formats, there are a
few where we have to bind as a different format and manually convert the
data.

Make sense?

--Jason

> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> Cc: Jason Ekstrand <jason.ekstrand at intel.com>
> ---
>  src/intel/vulkan/anv_formats.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/src/intel/vulkan/anv_formats.c
b/src/intel/vulkan/anv_formats.c
> index b26e48a..1a3b19d 100644
> --- a/src/intel/vulkan/anv_formats.c
> +++ b/src/intel/vulkan/anv_formats.c
> @@ -514,18 +514,13 @@ VkResult anv_GetPhysicalDeviceImageFormatProperties(
>        }
>     }
>
> -#if 0
>     if (usage & VK_IMAGE_USAGE_TRANSFER_DST_BIT) {
> -      if (anv_format_for_vk_format(format)->has_stencil) {
> -         /* Not yet implemented because copying to a W-tiled surface is
crazy
> -          * hard.
> -          */
> -         anv_finishme("support VK_IMAGE_USAGE_TRANSFER_DST_BIT for "
> -                      "stencil format");
> +      /* Meta implements transfers by rendering to the attachment image.
*/
> +      if (!(format_feature_flags &
(VK_FORMAT_FEATURE_COLOR_ATTACHMENT_BIT |
> +
VK_FORMAT_FEATURE_DEPTH_STENCIL_ATTACHMENT_BIT))) {
>           goto unsupported;
>        }
>     }
> -#endif
>
>     if (usage & VK_IMAGE_USAGE_SAMPLED_BIT) {
>        if (!(format_feature_flags & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT))
{
> --
> 2.8.1
>
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