On Tue, May 18, 2010 at 10:42 PM, Roland Scheidegger <srol...@vmware.com>wrote:
> On 18.05.2010 22:23, Dave Airlie wrote: > > On Wed, May 19, 2010 at 3:04 AM, Roland Scheidegger <srol...@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). > >> > >> Comments? > > > > I was worried overlapping blits for u_blitter were no longer allowed, > > this is a requirement so please don't break that if you find its in > > the way. > > I was thinking about changing the u_blitter code (I don't particularly > like that there is all different code to u_blit but doing pretty much > the same), but I left this as is (and there are no plans to change > u_blit code to not handle overlap). > That said though I can't see why u_blitter code still needs to handle > overlap. Unless I'm missing something overlap can no longer happen > there, at least not in master where r300 is the only user of this. > I recall that overlapping surface_copy blits were required by st/xorg. Since you said that the overlapping blits are no longer permitted, the corresponding code can be removed from u_blitter. -Marek
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