[Glamor] Discussing DRI3 support

[zhigang gong]

On Sat, Nov 30, 2013 at 3:23 AM, <davyaxel at free.fr> wrote:

> >    Could you tell more detail about when the texture may be of wrong
> format?
> On intel, creating the texture with the GL_RGBA format creates an ARGB8888
> texture.
> However on gallium drivers, it creates an ABGR8888 texture.
>
> >  I think, we still need to try our best to eliminate that one time extra
> copy if possible. Another special case which I really don't want to put it
> to the glamor_egl
> > side is the large pixmap which may allocate a texture array for it.
> >
> >     so I need to have glamor_egl_dri3_fd_from_pixmap in glamor.c,
> >     which would get the texture and check the type, and then call a
> glamor_egl function
> >     to create the fd.
> >
> >  The same issue why we could not use the texture->image->gbm_bo->fd
> solution?
> The solution I was first proposing, was, everytime we need a texture, and
> the asked format is GL_RGBA, and dri3 support is enabled, to call an egl
> function to get the texture, and be sure it is ARGB8888.
>
> I did a first implementation, in which I do not store the gbm_bo with the
> pixmap:
>
> Concretely, _glamor_create_tex(glamor_fbo.c) becomes that:
>
> static int
> _glamor_create_tex(glamor_screen_private *glamor_priv,
>            int w, int h, GLenum format)
> {
>     glamor_gl_dispatch *dispatch;
>     unsigned int tex = 0;
>
>     /* With dri3, we want to allocate ARGB8888 pixmaps only.
>      * Depending on the implementation, GL_RGBA might not
>      * give use ARGB8888. We ask glamor_egl to get
>      * an ARGB8888 based texture for us. */
>     if (glamor_priv->dri3_enabled && format == GL_RGBA)
>     {
>         tex = glamor_egl_create_argb8888_based_texture(glamor_priv->screen,
>                                 w, h);
>
    }
>     if (!tex)
>     {
>         dispatch = glamor_get_dispatch(glamor_priv);
>         dispatch->glGenTextures(1, &tex);
>         dispatch->glBindTexture(GL_TEXTURE_2D, tex);
>         dispatch->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
>                       GL_NEAREST);
>         dispatch->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
>                         GL_NEAREST);
>         dispatch->glTexImage2D(GL_TEXTURE_2D, 0, format, w, h, 0,
>                        format, GL_UNSIGNED_BYTE, NULL);
>         glamor_put_dispatch(glamor_priv);
>     }
>     return tex;
> }
>
> Here I don't store the gbm_bo glamor_egl side, since I don't have access
> to the pixmap.
> With this I'm sure that texture->image->gbm_bo will give the correct
> format later, on exportable pixmaps ( for pixmaps of depth 24 or 32, ie for
> which we create the texture with the GL_RGBA format).
>
> This includes the large pixmaps case, etc. And we don't need to call
> glamor_egl when destructing the pixmap since the gbm_bo to create the
> texture was destroyed.
>
> This solution doesn't need any copy when we want to export the pixmap, and
> do not store an image of the texture when the pixmap was never exported.
> Since _glamor_create_tex isn't called when the DDX creates a textured
> pixmap, the DDX can still create its own pixmaps.
>
> I have written an implementation with it, but I have issues with the
> enabling of dri3:
> If I bypass the negocation to enable dri3 between glamor and glamor_egl, I
> have a working implementation.
>
> Do you want I keep working on this solution?
>
 It looks good to me. Only one minor concern is that it calls to glamor_egl
function directly.  But I'm ok with it currently. Please go ahead.
 Thanks for your contribution.
 Zhigang Gong.

>
> Axel Davy
>
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