[Mesa-stable] [Mesa-dev] [PATCH 05/14] meta: Abort meta pbo path if readpixels need signed-unsigned conversion

[Iago Toral]

On Mon, 2015-07-20 at 10:56 -0700, Anuj Phogat wrote:
> On Mon, Jul 20, 2015 at 5:10 AM, Iago Toral <itoral at igalia.com> wrote:
> > On Fri, 2015-06-19 at 13:40 -0700, Anuj Phogat wrote:
> >> On Tue, Jun 16, 2015 at 9:21 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> >> >
> >> > On Jun 16, 2015 11:15, "Anuj Phogat" <anuj.phogat at gmail.com> wrote:
> >> >>
> >> >> Without this patch, piglit test fbo_integer_readpixels_sint_uint fails,
> >> >> when
> >> >> forced to use the 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 | 3 +++
> >> >>  1 file changed, 3 insertions(+)
> >> >>
> >> >> diff --git a/src/mesa/drivers/common/meta_tex_subimage.c
> >> >> b/src/mesa/drivers/common/meta_tex_subimage.c
> >> >> index 00364f8..84cbc50 100644
> >> >> --- a/src/mesa/drivers/common/meta_tex_subimage.c
> >> >> +++ b/src/mesa/drivers/common/meta_tex_subimage.c
> >> >> @@ -283,6 +283,9 @@ _mesa_meta_pbo_GetTexSubImage(struct gl_context *ctx,
> >> >> GLuint dims,
> >> >>
> >> >>        if (_mesa_need_rgb_to_luminance_conversion(rb->Format, format))
> >> >>           return false;
> >> >> +
> >> >> +      if (_mesa_need_signed_unsigned_int_conversion(rb->Format, format,
> >> >> type))
> >> >> +         return false;
> >> >
> >> > Hrm... This seems fishy.  Isn't glBlitFramebuffers supposed to handle format
> >> > conversion with integers?  If so we should probably fix it rather than just
> >> > skip it for the meta pbo path.
> >> >
> >> As discussed offline, here is relevant text for glBlitFrameBuffer() from
> >> OpenGL 4.5 spec, section 18.3.1:
> >> "An INVALID_OPERATION error is generated if format conversions are not
> >> supported, which occurs under any of the following conditions:
> >> -The read buffer contains fixed-point or floating-point values and any draw
> >>   buffer contains neither fixed-point nor floating-point values.
> >> -The read buffer contains unsigned integer values and any draw buffer does
> >>   not contain unsigned integer values.
> >> - The read buffer contains signed integer values and any draw buffer does
> >>   not contain signed integer values."
> >>
> >> I'll add a comment here explaining the reason to avoid meta path.
> >
> > Is this code going to run only for glBlitFramebuffer? I see this
> > function being called from code paths that implement glReadPixels and
> > glGetTexImage too.
> >
> _mesa_meta_pbo_GetTexSubImage() is used only for glReadPixels and
> glGetTexImage. I quoted the glBliFrameBuffer restriction above because
> the function is later using _mesa_meta_BlitFramebuffer(), which doesn't
> support some format conversions.

If this function can be used to resolve ReadPixels and GetTexImage but
the checks you add are *specific* to BlitFramebuffer, it does not look
like this is the right place for them. Shouldn't you put them inside
_mesa_meta_BlitFramebuffer instead? Otherwise they would affect to
ReadPixels and GetTexImage too and I don't see the same restrictions
applying to ReadPixels for example.

Iago

> >> >>     }
> >> >>
> >> >>     /* For arrays, use a tall (height * depth) 2D texture but taking into
> >> >> --
> >> >> 1.9.3
> >> >>
> >> >> _______________________________________________
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> >
> >
>