[Mesa-dev] [PATCH 02/14] meta: Fix transfer operations check in meta pbo path for readpixels

[Iago Toral]

On Tue, 2015-06-16 at 11:15 -0700, Anuj Phogat wrote:
> Without this patch, arb_color_buffer_float-readpixels test fails, when
> forced to use meta pbo path.
> 
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> Cc: <mesa-stable at lists.freedesktop.org>
> ---
>  src/mesa/drivers/common/meta_tex_subimage.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/src/mesa/drivers/common/meta_tex_subimage.c b/src/mesa/drivers/common/meta_tex_subimage.c
> index d2474f5..00364f8 100644
> --- a/src/mesa/drivers/common/meta_tex_subimage.c
> +++ b/src/mesa/drivers/common/meta_tex_subimage.c
> @@ -273,12 +273,14 @@ _mesa_meta_pbo_GetTexSubImage(struct gl_context *ctx, GLuint dims,
>         format == GL_COLOR_INDEX)
>        return false;
>  
> -   if (ctx->_ImageTransferState)
> -      return false;
> -
> -

That test uses glReadPixels so it should call this with tex_image set to
NULL and it should flow through the if you have below. The call to
_mesa_get_readpixels_transfer_ops that you add below looks like it does
what we want for a pixel read from a framebuffer instead of simply
checking ctx->_ImageTransferState directly. I suppose this is what fixes
the test, right?

The patch also removes the ctx->_ImageTransferState check for the case
where we are reading from a real texture (tex_image != NULL), that seems
unrelated to fixing arb_color_buffer_float-readpixels... Looking at the
texture read code from getteximage.c it seems like this should be fine
since that file does not seem to use that field for anything either, so
I guess the check might not valid in this case.

I think it would be nice if you updated the changelog to explain these
things.

Iago

> +   /* Don't use meta path for readpixels in below conditions. */
>     if (!tex_image) {
>        rb = ctx->ReadBuffer->_ColorReadBuffer;
> +
> +      if (_mesa_get_readpixels_transfer_ops(ctx, rb->Format, format,
> +                                            type, GL_FALSE))
> +         return false;
> +
>        if (_mesa_need_rgb_to_luminance_conversion(rb->Format, format))
>           return false;
>     }