On Mon, Jan 22, 2018 at 06:39:52PM -0800, Jason Ekstrand wrote:
> On Mon, Jan 22, 2018 at 5:50 PM, Jason Ekstrand <ja...@jlekstrand.net>
> wrote:
>
> > On Mon, Jan 22, 2018 at 11:31 AM, Nanley Chery <nanleych...@gmail.com>
> > wrote:
> >
> >> On Fri, Jan 19, 2018 at 03:47:26PM -0800, Jason Ekstrand wrote:
> >> > This moves it to being based on layout_to_aux_usage instead of being
> >> > hard-coded based on bits of a priori knowledge of how transitions
> >> > interact with layouts. This conceptually simplifies things because
> >> > we're now using layout_to_aux_usage and layout_supports_fast_clear to
> >> > make resolve decisions so changes to those functions will do what one
> >> > expects.
> >> >
> >> > This fixes a potential bug with window system integration on gen9+ where
> >> ^
> >> This patch still doesn't fix the bug.
> >>
> >
> > Yup. I've changed this paragraph to:
> >
> > There is a potential bug with window system integration on gen9+ where
> > we wouldn't do a resolve when transitioning to the PRESENT_SRC layout
> > because we just assume that everything that handles CCS_E can handle it
> > all the time. When handing a CCS_E image off to the window system, we
> > may need to do a full resolve if the window system does not support the
> > CCS_E modifier. The only reason why this hasn't been a problem yet is
> > because we don't support modifiers in Vulkan WSI and so we always get X
> > tiling which implies no CCS on gen9+. This patch doesn't actually fix
> > that bug yet but it takes us the first step in that direction by making
> > us actually pick the correct resolve op. In order to handle all of the
> > cases, we need more detailed aux tracking.
> >
> >
Sounds good.
> >> > we wouldn't do a resolve when transitioning to the PRESENT_SRC layout
> >> > because we just assume that everything that handles CCS_E can handle it
> >> > all the time. When handing a CCS_E image off to the window system, we
> >> > may need to do a full resolve if the window system does not support the
> >> > CCS_E modifier. The only reason why this hasn't been a problem yet is
> >> > because we don't support modifiers in Vulkan WSI and so we always get X
> >> > tiling which implies no CCS on gen9+.
> >> >
> >> > v2 (Jason Ekstrand):
> >> > - Make a few more things const
> >> > - Use the anv_fast_clear_support enum
> >> >
> >> > Reviewed-by: Topi Pohjolainen <topi.pohjolai...@intel.com>
> >> > ---
> >> > src/intel/vulkan/genX_cmd_buffer.c | 56 ++++++++++++++++++++++++++++++
> >> --------
> >> > 1 file changed, 44 insertions(+), 12 deletions(-)
> >> >
> >> > diff --git a/src/intel/vulkan/genX_cmd_buffer.c
> >> b/src/intel/vulkan/genX_cmd_buffer.c
> >> > index 6a6d8b2..fd27463 100644
> >> > --- a/src/intel/vulkan/genX_cmd_buffer.c
> >> > +++ b/src/intel/vulkan/genX_cmd_buffer.c
> >> > @@ -593,6 +593,7 @@ transition_color_buffer(struct anv_cmd_buffer
> >> *cmd_buffer,
> >> > VkImageLayout initial_layout,
> >> > VkImageLayout final_layout)
> >> > {
> >> > + const struct gen_device_info *devinfo = &cmd_buffer->device->info;
> >> > /* Validate the inputs. */
> >> > assert(cmd_buffer);
> >> > assert(image && image->aspects & VK_IMAGE_ASPECT_ANY_COLOR_BIT_
> >> ANV);
> >> > @@ -733,17 +734,51 @@ transition_color_buffer(struct anv_cmd_buffer
> >> *cmd_buffer,
> >> > VK_IMAGE_LAYOUT_COLOR_ATTACHM
> >> ENT_OPTIMAL,
> >> > final_layout);
> >> > }
> >> > - } else if (initial_layout !=
> >> > VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL)
> >> {
> >> > - /* Resolves are only necessary if the subresource may contain
> >> blocks
> >> > - * fast-cleared to values unsupported in other layouts. This
> >> only occurs
> >> > - * if the initial layout is COLOR_ATTACHMENT_OPTIMAL.
> >> > - */
> >> > - return;
> >> > - } else if (image->samples > 1) {
> >> > - /* MCS buffers don't need resolving. */
> >> > return;
> >> > }
> >> >
> >> > + /* If initial aux usage is NONE, there is nothing to resolve */
> >> > + const enum isl_aux_usage initial_aux_usage =
> >> > + anv_layout_to_aux_usage(devinfo, image, aspect, initial_layout);
> >> > + if (initial_aux_usage == ISL_AUX_USAGE_NONE)
> >> > + return;
> >> > +
> >> > + enum isl_aux_op resolve_op = ISL_AUX_OP_NONE;
> >> > +
> >> > + /* If the initial layout supports more fast clear than the final
> >> layout
> >> > + * then we need at least a partial resolve.
> >> > + */
> >> > + const enum anv_fast_clear_type initial_fast_clear =
> >> > + anv_layout_to_fast_clear_type(devinfo, image, aspect,
> >> initial_layout);
> >> > + const enum anv_fast_clear_type final_fast_clear =
> >> > + anv_layout_to_fast_clear_type(devinfo, image, aspect,
> >> final_layout);
> >> > + if (final_fast_clear < initial_fast_clear)
> >> > + resolve_op = ISL_AUX_OP_PARTIAL_RESOLVE;
> >> > +
> >> > + const enum isl_aux_usage final_aux_usage =
> >> > + anv_layout_to_aux_usage(devinfo, image, aspect, final_layout);
> >> > + if (initial_aux_usage == ISL_AUX_USAGE_CCS_E &&
> >> > + final_aux_usage != ISL_AUX_USAGE_CCS_E)
> >> > + resolve_op = ISL_AUX_OP_FULL_RESOLVE;
> >> > +
> >> > + /* CCS_D only supports full resolves and BLORP will assert on us if
> >> we try
> >> > + * to do a partial resolve on a CCS_D surface.
> >> > + */
> >> > + if (resolve_op == ISL_AUX_OP_PARTIAL_RESOLVE &&
> >> > + initial_aux_usage == ISL_AUX_USAGE_CCS_D)
> >> > + resolve_op = ISL_AUX_OP_FULL_RESOLVE;
> >> > +
> >> > + if (resolve_op == ISL_AUX_OP_NONE)
> >> > + return;
> >> > +
> >> > + /* Even though the above code can theoretically handle multiple
> >> resolve
> >> > + * types such as CCS_D -> CCS_E, the predication code below can't.
> >> We only
> >> > + * really handle a couple of cases.
> >> > + */
> >> > + assert(initial_aux_usage == ISL_AUX_USAGE_NONE ||
> >> > + final_aux_usage == ISL_AUX_USAGE_NONE ||
> >> > + initial_aux_usage == final_aux_usage);
> >> > +
> >>
> >> I'm finding this assertion and comment confusing.
> >
> >
> > You and Topi both!
> >
> >
> >> The comment says that
> >> the predication code below can't handle CCS_D -> CCS_E (which requires a
> >> no-op resolve), but the assertion below it allows initial_aux_usage to
> >> be NONE (which would lead to a no-op resolve), and initial_aux_usage ==
> >> final_aux_usage which (may lead to a no-op resolve).
> >>
> >> As far as I can tell, the only problematic case this assertion would catch
> >> is a CCS_E -> CCS_D transition. This transition requires a FULL_RESOLVE.
> >> If
> >> the CCS_E texture was fast-cleared to transparent black then the
> >> needs_resolve predicate would be set false. In this case a resolve would
> >> not occur when it should. Unfortunately, this assertion does allow the
> >> case of CCS_E -> NONE which has the same problem as CCS_E -> CCS_D.
> >>
> >
> > Ok, let me make things a bit more clear. After reading what you wrote and
> > what Topi wrote and the code, my memory is jogged as to exactly why I made
> > the assert the way I did.
> >
> > The if condition above this which selects partial resolves makes the
> > assumption that we don't ever mix CCS_E and CCS_D. For a given image, it
> > can only have one of two aux_usages: NONE and one of CCS_E or CCS_D. If we
> > want to handle mixing CCS_E and CCS_D, we may need more complex logic like
> > in i965.
> >
> > It's entirely possible that the above condition actually does work in all
> > the cases where CCS_E and CCS_D are mixed but I haven't thought about it
> > long enough to determine if that is the case. What I really wanted to do
> > was to assert that we don't have CCS_E/D mixing. Does that make more sense?
> >
> > Also, I think I said I would break this out into a helper function to make
> > it make more sense. I'll do that, make the assert make more sense, and
> > send out a v3.
> >
>
> Gah! As I was working on this, I realized that the reason I hadn't broken
> it out into a separate function is that we need some of the intermediate
> results for actually building the predicate and doing the resolve. What I
> propose to do is to move the assert up above the "if (initial_aux_usage ==
> ISL_AUX_USAGE_NONE) return;" and change the comment to the following:
>
> /* The current code assumes that there is no mixing of CCS_E and CCS_D.
> * We can handle transitions between CCS_D/E to and from NONE. What we
> * don't yet handle is switching between CCS_E and CCS_D within a given
> * image. Doing so in a performant way requires more detailed aux state
> * tracking such as what is done in i965. For now, just assume that we
> * only have one type of compression.
> */
>
>
This change looks good. Though, if I'm not mistaken, we'll have enough aux
tracking to do the transition in a performant manner by
the end of the series right?
-Nanley
> > Perhaps we should update the comment to note the difficulty in
> >> transitioning from CCS_E and assert:
> >>
> >> if (initial_aux_usage == ISL_AUX_USAGE_CCS_E)
> >> assert(final_aux_usage == ISL_AUX_USAGE_CCS_E);
> >>
> >> -Nanley
> >>
> >> > /* Perform a resolve to synchronize data between the main and aux
> >> buffer.
> >> > * Before we begin, we must satisfy the cache flushing requirement
> >> specified
> >> > * in the Sky Lake PRM Vol. 7, "MCS Buffer for Render Target(s)":
> >> > @@ -774,10 +809,7 @@ transition_color_buffer(struct anv_cmd_buffer
> >> *cmd_buffer,
> >> > genX(load_needs_resolve_predicate)(cmd_buffer, image, aspect,
> >> level);
> >> >
> >> > anv_image_ccs_op(cmd_buffer, image, aspect, level,
> >> > - base_layer, layer_count,
> >> > - image->planes[plane].aux_usage ==
> >> ISL_AUX_USAGE_CCS_E ?
> >> > - ISL_AUX_OP_PARTIAL_RESOLVE :
> >> ISL_AUX_OP_FULL_RESOLVE,
> >> > - true);
> >> > + base_layer, layer_count, resolve_op, true);
> >> >
> >> > genX(set_image_needs_resolve)(cmd_buffer, image, aspect, level,
> >> false);
> >> > }
> >> > --
> >> > 2.5.0.400.gff86faf
> >> >
> >> > _______________________________________________
> >> > mesa-dev mailing list
> >> > mesa-dev@lists.freedesktop.org
> >> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >>
> >
> >
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