On Wed, Nov 23, 2016 at 09:05:39AM -0800, Jason Ekstrand wrote: > On Wed, Nov 23, 2016 at 1:16 AM, Topi Pohjolainen > <[1]topi.pohjolai...@gmail.com> wrote: > > Originally re-clears where skipped but when lossless compression > was introduced the re-clears where errorneously enabled also for > non-compressed fast clears. > Signed-off-by: Topi Pohjolainen <[2]topi.pohjolai...@intel.com> > CC: Ben Widawsky <[3]benjamin.widaw...@intel.com> > CC: Kenneth Graunke <[4]kenn...@whitecape.org> > CC: Harri Syrja <[5]harri.sy...@intel.com> > Cc: Chad Versace <[6]c...@kiwitree.net> > --- > src/mesa/drivers/dri/i965/brw_blorp.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > diff --git a/src/mesa/drivers/dri/i965/brw_blorp.c > b/src/mesa/drivers/dri/i965/brw_blorp.c > index 556f2c0..9a849f5 100644 > --- a/src/mesa/drivers/dri/i965/brw_blorp.c > +++ b/src/mesa/drivers/dri/i965/brw_blorp.c > @@ -825,10 +825,23 @@ do_single_blorp_clear(struct brw_context *brw, > struct gl_framebuffer *fb, > brw, &irb->mt->gen9_fast_clear_ > color, > &override_color); > - /* If the buffer is already in INTEL_FAST_CLEAR_STATE_CLEAR, > the clear > - * is redundant and can be skipped. > + /* If the buffer is already in INTEL_FAST_CLEAR_STATE_CLEAR, > and the > + * buffer isn't compressed, the clear is redundant and can be > skipped. > + * > + * Without compression fast clear only operates on the mcs > buffer > + * recording if color values are cleared. The hardware, > however, > + * doesn't write the actual color value into the mcs or color > + * buffer. Only by the time of render (inclucing color > resolve) does the > + * hardware read the _current_ color value in the surface > state and > + * write the actual pixel values in the color buffer > accordingly. > + * > + * This seems to be the reason why sampler engine cannot > handle > + * non-compressed fast clear - it doesn't know how to read > the color > + * value from the surface state. With compression the color > value is > + * recorded in the color buffer (only not for every pixel) > and therefore > + * it is available without consulting the surface state. > > This doesn't jive with my understanding of fast clears on gen9. > Everything I've seen so far indicates that the clear color in the > surface state *does* matter. Otherwise, why would it be there? In > particular, my understanding of the 2-bit CCS values is that 0 means > resolved, 1 means compressed and 3 means clear where "clear" means "go > look at the clear color". Have you done experiments that lead you to > some other conclusion?
Right, you are correct. This is actually a patch from really early days when I didn't know any better. We might want to drop this for now, there is the 0/1 color thing for sampler engine that we probably need to fix first anyway. What do you think? > > */ > - if (!color_updated && > + if ((!color_updated || !is_lossless_compressed) && > irb->mt->fast_clear_state == > INTEL_FAST_CLEAR_STATE_CLEAR) > return true; > -- > 2.5.5 > _______________________________________________ > mesa-dev mailing list > [7]mesa-dev@lists.freedesktop.org > [8]https://lists.freedesktop.org/mailman/listinfo/mesa-dev > > References > > 1. mailto:topi.pohjolai...@gmail.com > 2. mailto:topi.pohjolai...@intel.com > 3. mailto:benjamin.widaw...@intel.com > 4. mailto:kenn...@whitecape.org > 5. mailto:harri.sy...@intel.com > 6. mailto:c...@kiwitree.net > 7. mailto:mesa-dev@lists.freedesktop.org > 8. https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
