[Mesa-dev] [PATCH 3/5] i965: Check base format to determine whether to use tiled memcpy

[Ben Widawsky]

On Thu, Nov 19, 2015 at 04:25:19PM +0100, Neil Roberts wrote:
> The tiled memcpy doesn't work for copying from RGBX to RGBA because it
> doesn't override the alpha component to 1.0. Commit 2cebaac479d4 added
> a check to disable it for RGBX formats by looking at the TexFormat.
> However a lot of the rest of the code base is written with the
> assumption that an RGBA texture can be used internally to implement a
> GL_RGB texture. If that is done then this check breaks. This patch
> makes it instead check the base format of the texture which I think
> more directly matches the intention.
> 
> Cc: Jason Ekstrand <jason.ekstrand at intel.com>


I really don't know the corner cases well enough, but concept seems good to me.
In particular, I assume this is now going to return false for more cases than
previously - and that's okay, I guess?

> ---
>  src/mesa/drivers/dri/i965/intel_pixel_read.c | 7 ++++---
>  src/mesa/drivers/dri/i965/intel_tex_image.c  | 7 ++++---
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_pixel_read.c b/src/mesa/drivers/dri/i965/intel_pixel_read.c
> index 9bcbbd1..c8aef65 100644
> --- a/src/mesa/drivers/dri/i965/intel_pixel_read.c
> +++ b/src/mesa/drivers/dri/i965/intel_pixel_read.c
> @@ -135,10 +135,11 @@ intel_readpixels_tiled_memcpy(struct gl_context * ctx,
>        return false;
>  
>     /* We can't handle copying from RGBX or BGRX because the tiled_memcpy
> -    * function doesn't set the last channel to 1.
> +    * function doesn't set the last channel to 1. Note this checks BaseFormat
> +    * rather than TexFormat in case the RGBX format is being simulated with an
> +    * RGBA format.
>      */
> -   if (rb->Format == MESA_FORMAT_B8G8R8X8_UNORM ||
> -       rb->Format == MESA_FORMAT_R8G8B8X8_UNORM)
> +   if (rb->_BaseFormat == GL_RGB)
>        return false;
>  
>     if (!intel_get_memcpy(rb->Format, format, type, &mem_copy, &cpp,
> diff --git a/src/mesa/drivers/dri/i965/intel_tex_image.c b/src/mesa/drivers/dri/i965/intel_tex_image.c
> index 34b91e8..e3710da7 100644
> --- a/src/mesa/drivers/dri/i965/intel_tex_image.c
> +++ b/src/mesa/drivers/dri/i965/intel_tex_image.c
> @@ -399,10 +399,11 @@ intel_gettexsubimage_tiled_memcpy(struct gl_context *ctx,
>        return false;
>  
>     /* We can't handle copying from RGBX or BGRX because the tiled_memcpy
> -    * function doesn't set the last channel to 1.
> +    * function doesn't set the last channel to 1. Note this checks BaseFormat
> +    * rather than TexFormat in case the RGBX format is being simulated with an
> +    * RGBA format.
>      */
> -   if (texImage->TexFormat == MESA_FORMAT_B8G8R8X8_UNORM ||
> -       texImage->TexFormat == MESA_FORMAT_R8G8B8X8_UNORM)
> +   if (texImage->_BaseFormat == GL_RGB)
>        return false;
>  
>     if (!intel_get_memcpy(texImage->TexFormat, format, type, &mem_copy, &cpp,
> -- 
> 1.9.3
>