Nouveau - May 2010 - [Mesa-dev] RFC: gallium-msaa branch merge

On Tue, May 18, 2010 at 7:04 PM, Roland Scheidegger <sroland at
vmware.com> wrote:
> Hi,
>
> I plan to merge the gallium-msaa branch to master soon.
> It's actually a bit of a misnomer since the conceptually more important
> changes in there are about blits...
>
> Here's a short summary what this is about:
> blits now operate on resources, not surfaces (surface_copy/fill ->
> resource_copy/fill_region). Note that overlapping blits are no longer
> permitted (half the code always assumed this wasn't the case), and
these
> functions are now mandatory (most of the code using these just checked
> for their presence and if not used util_surface_copy instead, hence it
> seems cleaner if drivers plug that in themselves, which some already did).
> Also, there's an assumption that resource_copy_region works regardless
> of bind flags (at least for texture targets, actually might also need to
> work for buffers for "modern" drivers in the future not sure
yet), hence
> there are no longer any PIPE_BIND_BLIT flags (which were quite magic to
> begin with, since a lot of the code could end up with a quad blit which
> really wants RENDER_TARGET/SAMPLER_VIEW bind flags instead).
> It is possible some of the drivers implementation are a bit suboptimal
> now, as they still use surfaces internally for easier migration (svga,
> r300g, nouveau might particularly benefit from some cleanup).
> If a driver implements this just with util_resource_copy_region, it is
> possible there are performance regressions, since some (certainly not
> all) state trackers used a quad blitter instead if this wasn't
available.
> The u_blit code still uses a pipe_surface as destination, which should
> probably be changed at some point too but the change was already big
> enough imho.
>
> Historically, blits had to operate on surfaces IIRC since there actually
> were surfaces in gallium not backed by a pipe_resource (then
> pipe_texture) but those are gone. So get_tex_surface() should actually
> be viewed as the analogous function to create_sampler_view() (and yes it
> will migrate to context too and probably renamed to something else), it
> creates a view of a resource (the pipe_surface) to be used as a render
> target (color or depth/stencil).
>
> The msaa changes are fairly minimal, there's a new context function to
> set the sample mask (all drivers have dummy implementations), plus some
> bits for sample to coverage etc. And a explicit resource_resolve
> function which is defined as the only way to resolve a multisampled
> resource, but so far no driver implements multisampling (and the mesa
> state tracker won't use it neither).
>
Just including nouveau ML in CC in case someone missed that merge, as
I think there is some work to be done in nouveau driver.

Ok, after looking at how some other drivers were updated, I thought
nouveau needed bigger changes than that.
Jakob just pushed a simple build fix, and now nv50 builds and runs (almost ;)).

I just noticed 5 piglit regressions :
fbo/fbo-copypix
fbo/fbo-copyteximage
general/scissor-copypixels
texturing/depth-level-clamp
texturing/texredefine


And I am not sure how important is the TODO mentioned in the commit log below.

commit b59b23a51dc17da59ccff0b3f8a73009056746e5
Author: Roland Scheidegger <sroland at vmware.com>
Date:   Mon May 17 21:28:14 2010 +0200

    nouveau: adapt to interface changes

    this probably needs further cleanup (just getting a surface for the resource
    seems quite nonoptimal and potentially cause unnecessary copies I think)

On 21.05.2010 23:40, Xavier Chantry wrote:
> Ok, after looking at how some other drivers were updated, I thought
> nouveau needed bigger changes than that.
> Jakob just pushed a simple build fix, and now nv50 builds and runs (almost
;)).
> 
> I just noticed 5 piglit regressions :
> fbo/fbo-copypix
> fbo/fbo-copyteximage
> general/scissor-copypixels
> texturing/depth-level-clamp
> texturing/texredefine
> 
> 
> And I am not sure how important is the TODO mentioned in the commit log
below.
> 
> commit b59b23a51dc17da59ccff0b3f8a73009056746e5
> Author: Roland Scheidegger <sroland at vmware.com>
> Date:   Mon May 17 21:28:14 2010 +0200
> 
>     nouveau: adapt to interface changes
> 
>     this probably needs further cleanup (just getting a surface for the
resource
>     seems quite nonoptimal and potentially cause unnecessary copies I
think)
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
There was some logic in nouveau which decided when to update "shadow"
surfaces (which looked a bit odd at places). That used blit flags, and
since they are gone this might not really do what it used to do. I think
if it were changed to no longer use surfaces internally for copying this
would become much more obvious what to do.

Roland