[Mesa-dev] [PATCH 24/32] i965/miptree: Allocate mt earlier in update winsys

[Pohjolainen, Topi]

On Wed, Jan 04, 2017 at 10:26:50AM +0200, Pohjolainen, Topi wrote:
> On Mon, Jan 02, 2017 at 06:37:15PM -0800, Ben Widawsky wrote:
> > Allows us to continue utilizing common miptree creation using __DRIimage
> > without creating a new DRIimage (for the intel_process_dri2_buffer()
> > case).
> > 
> > This is a bit ugly, but I think it's the best one can do.
> > 
> > Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> > Acked-by: Daniel Stone <daniels at collabora.com>
> > ---
> >  src/mesa/drivers/dri/i965/brw_context.c       | 31 +++++++++++++++++++++++----
> >  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 17 ++-------------
> >  src/mesa/drivers/dri/i965/intel_mipmap_tree.h |  2 +-
> >  3 files changed, 30 insertions(+), 20 deletions(-)
> > 
> > diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> > index 7e350c4e47..ce01605826 100644
> > --- a/src/mesa/drivers/dri/i965/brw_context.c
> > +++ b/src/mesa/drivers/dri/i965/brw_context.c
> > @@ -1652,10 +1652,24 @@ intel_process_dri2_buffer(struct brw_context *brw,
> >        return;
> >     }
> >  
> > -   if (!intel_update_winsys_renderbuffer_miptree(brw, rb, bo,
> > +   struct intel_mipmap_tree *mt = intel_miptree_create_for_bo(brw,
> > +                                                              bo,
> > +                                                              intel_rb_format(rb),
> > +                                                              0,
> > +                                                              drawable->w,
> > +                                                              drawable->h,
> > +                                                              1,
> > +                                                              buffer->pitch,
> > +                                                              MIPTREE_LAYOUT_FOR_SCANOUT);
> 
> I chose this patch to discuss the window system integration which I know very
> little about. So here goes:
> 
> After this patch MIPTREE_LAYOUT_FOR_SCANOUT gets set from two places:
> here and from intel_miptree_create_for_renderbuffer().
> 
> This flag results into mt->is_scanout getting set and corresponding dri images
> passed to external consumption fast color cleared but compressed. 
> 
> Effectively intel_mipmap_tree::is_scanout now means that the external party
> is compression aware meaning gpu or display controller. Could we add some
> explanation to intel_mipmap_tree.h? Current description for is_scanout is:
> 
>  /**
>   * Tells if the underlying buffer is to be also consumed by entities other
>   * than the driver. This allows logic to turn off features such as lossless
>   * compression which is not currently understood by client applications.
>   */
> 
> Big question for me is that how do DRI2 clients tell compressed buffers are
> understood? 

All these scanout buffers originate from outside, and if they come with
auxiliary, it is clear that compression is supported. Is it that simple in the
end?