panfrost: Adjust the format for AFBC textures on Bifrost v7

On Bifrost v7, AFBC textures can't be used with a non-identity component
order. Let's patch the format so the component order is always RGB[A].
That means we're lying about the internal format, but that shouldn't be
a problem as long as we don't share the resource.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8125>

src/gallium/drivers/panfrost/pan_mfbd.c

@@ -83,13 +83,20 @@ panfrost_mfbd_raw_format(unsigned bits)
 }
 
 static void
-panfrost_mfbd_rt_init_format(struct pipe_surface *surf,
+panfrost_mfbd_rt_init_format(const struct panfrost_device *dev,
+                             struct pipe_surface *surf,
                              struct MALI_RENDER_TARGET *rt)
 {
+        struct panfrost_resource *rsrc = pan_resource(surf->texture);
+        enum pipe_format format =
+                drm_is_afbc(rsrc->layout.modifier) ?
+                panfrost_afbc_format_fixup(dev, surf->format) :
+                surf->format;
+
         /* Explode details on the format */
 
         const struct util_format_description *desc =
-                util_format_description(surf->format);
+                util_format_description(format);
 
         /* The swizzle for rendering is inverted from texturing */
 
@@ -149,7 +156,7 @@ panfrost_mfbd_rt_set_buf(struct pipe_surface *surf,
         else
                 rt->writeback_msaa = MALI_MSAA_SINGLE;
 
-        panfrost_mfbd_rt_init_format(surf, rt);
+        panfrost_mfbd_rt_init_format(dev, surf, rt);
 
         if (rsrc->layout.modifier == DRM_FORMAT_MOD_LINEAR) {
                 if (version >= 7)

src/gallium/drivers/panfrost/pan_resource.c

@@ -127,7 +127,18 @@ panfrost_resource_from_handle(struct pipe_screen *pscreen,
                 rsc->checksummed = true;
         }
 
+        /* If we import an AFBC resource, it should be in a format that's
+         * supported, otherwise we don't know if the fixup is expected to be
+         * applied or not. In practice that's not a problem if the buffer has
+         * been exported by the GPU because the same constraint applies to both
+         * ends, but we might have issues if the exporter is a different piece
+         * of hardware (VPU?) that supports the BGR variants.
+         */
+        assert(!drm_is_afbc(whandle->modifier) ||
+               !panfrost_afbc_format_needs_fixup(dev, rsc->internal_format));
+
         if (drm_is_afbc(whandle->modifier)) {
+
                 unsigned tile_w =
                         panfrost_block_dim(whandle->modifier, true, 0);
                 unsigned tile_h =
@@ -163,6 +174,16 @@ panfrost_resource_get_handle(struct pipe_screen *pscreen,
         struct panfrost_resource *rsrc = (struct panfrost_resource *) pt;
         struct renderonly_scanout *scanout = rsrc->scanout;
 
+        /* If we export an AFBC resource, it should be in a format that's
+         * supported, otherwise the importer has no clue about the format fixup
+         * done internally. In practice that shouldn't be an issue for GPU
+         * buffers because the same constraint applies to both ends, but we
+         * might have issues if the importer is a different piece of hardware
+         * that supports BGR variants.
+         */
+        assert(!drm_is_afbc(rsrc->layout.modifier) ||
+               !panfrost_afbc_format_needs_fixup(dev, rsrc->internal_format));
+
         handle->modifier = rsrc->layout.modifier;
         rsrc->modifier_constant = true;
 
@@ -519,6 +540,14 @@ panfrost_should_afbc(struct panfrost_device *dev, const struct panfrost_resource
         if (pres->base.width0 <= 16 && pres->base.height0 <= 16)
                 return false;
 
+        /* AFBC(BGR) is not natively supported on Bifrost v7+. When we don't
+         * share the buffer we can fake those formats since we're in control
+         * of the format/swizzle we apply to the textures/RTs.
+         */
+        if (panfrost_afbc_format_needs_fixup(dev, pres->internal_format) &&
+            (pres->base.bind & (PIPE_BIND_SCANOUT | PIPE_BIND_SHARED)))
+                return false;
+
         /* Otherwise, we'd prefer AFBC as it is dramatically more efficient
          * than linear or usually even u-interleaved */
         return true;

src/panfrost/lib/pan_afbc.c

@@ -140,3 +140,51 @@ panfrost_afbc_can_ytr(enum pipe_format format)
         /* The fourth channel if it exists doesn't matter */
         return desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB;
 }
+
+bool
+panfrost_afbc_format_needs_fixup(const struct panfrost_device *dev,
+                                 enum pipe_format format)
+{
+        if (dev->arch < 7)
+                return false;
+
+        const struct util_format_description *desc =
+                util_format_description(format);
+
+        bool identity_swizzle = true;
+        for (unsigned c = 0; c < desc->nr_channels; c++) {
+                if (desc->swizzle[c] != c) {
+                        identity_swizzle = false;
+                        break;
+                }
+        }
+
+        if (identity_swizzle ||
+            desc->colorspace == UTIL_FORMAT_COLORSPACE_ZS)
+                return false;
+
+        return true;
+}
+
+enum pipe_format
+panfrost_afbc_format_fixup(const struct panfrost_device *dev,
+                           enum pipe_format format)
+{
+        if (!panfrost_afbc_format_needs_fixup(dev, format))
+                return format;
+
+        const struct util_format_description *desc =
+                util_format_description(format);
+
+        switch (format) {
+        case PIPE_FORMAT_B8G8R8_UNORM:
+                return PIPE_FORMAT_R8G8B8_UNORM;
+        case PIPE_FORMAT_B5G6R5_UNORM:
+                return PIPE_FORMAT_R5G6B5_UNORM;
+        default:
+                if (util_format_is_rgba8_variant(desc))
+                        return PIPE_FORMAT_R8G8B8A8_UNORM;
+
+                unreachable("Invalid format");
+        }
+}

src/panfrost/lib/pan_texture.c

@@ -414,6 +414,10 @@ panfrost_new_texture(const struct panfrost_device *dev,
                      const struct panfrost_ptr *payload)
 {
         unsigned swizzle = panfrost_translate_swizzle_4(user_swizzle);
+
+        if (drm_is_afbc(layout->modifier))
+                format = panfrost_afbc_format_fixup(dev, format);
+
         const struct util_format_description *desc =
                 util_format_description(format);
 

src/panfrost/lib/pan_texture.h

@@ -112,6 +112,14 @@ panfrost_afbc_header_size(unsigned width, unsigned height);
 bool
 panfrost_afbc_can_ytr(enum pipe_format format);
 
+bool
+panfrost_afbc_format_needs_fixup(const struct panfrost_device *dev,
+                                 enum pipe_format format);
+
+enum pipe_format
+panfrost_afbc_format_fixup(const struct panfrost_device *dev,
+                           enum pipe_format format);
+
 unsigned
 panfrost_block_dim(uint64_t modifier, bool width, unsigned plane);