[Mesa-dev] [PATCH] i965: Allow the blorp blit between BGR and RGB

[Neil Roberts]

> FWIW, I relaxed the format restrictions in
> brw_blorp_copytexsubimage, so it can handle general format
> conversions as well (i.e. RGBA_FLOAT16 -> RGBA8888_UNORM). There's
> no reason we couldn't do that for BlitFramebuffer as well, I just
> forgot to do it (and then we decided to make it a newbie task, and
> then the newbie didn't do said task, and...oops.)

Ok, I think that is a good idea. Here is a patch to do it. I'm also
sending a test to the piglit mailing list that tries blitting between
different formats.

Regards,
- Neil

------- >8 --------------- (use git am --scissors to automatically chop here)
Subject: i965: Don't check for format differences when using the blorp blitter

Previously the blorp blitter wouldn't be used if the source and destination
buffer had a different format other than swizzling between RGB and BGR and
adding or removing a dummy alpha channel. However there's no reason why the
blorp code path can't be used to do almost all format conversions so this
patch just removes the checks. However it does explicitly disable converting
to/from MESA_FORMAT_Z24_UNORM_X8_UINT because there is a similar check
brw_blorp_copytexsubimage.

This doesn't cause any Piglit test regressions at least on Ivybridge.
---
 src/mesa/drivers/dri/i965/brw_blorp_blit.cpp | 66 +++++-----------------------
 1 file changed, 12 insertions(+), 54 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp b/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
index d7f5f7d..6a4918e 100644
--- a/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
+++ b/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
@@ -120,52 +120,6 @@ do_blorp_blit(struct brw_context *brw, GLbitfield buffer_bit,
 }
 
 static bool
-format_is_rgba_or_rgbx_byte(mesa_format format)
-{
-   switch (format) {
-   case MESA_FORMAT_B8G8R8X8_UNORM:
-   case MESA_FORMAT_B8G8R8A8_UNORM:
-   case MESA_FORMAT_R8G8B8X8_UNORM:
-   case MESA_FORMAT_R8G8B8A8_UNORM:
-      return true;
-   default:
-      return false;
-   }
-}
-
-static bool
-color_formats_match(mesa_format src_format, mesa_format dst_format)
-{
-   mesa_format linear_src_format = _mesa_get_srgb_format_linear(src_format);
-   mesa_format linear_dst_format = _mesa_get_srgb_format_linear(dst_format);
-
-   /* Normally, we require the formats to be equal. However, we also support
-    * blitting from ARGB to XRGB (discarding alpha), and from XRGB to ARGB
-    * (overriding alpha to 1.0 via blending) as well as swizzling between BGR
-    * and RGB.
-    */
-
-   return (linear_src_format == linear_dst_format ||
-           (format_is_rgba_or_rgbx_byte(linear_src_format) &&
-            format_is_rgba_or_rgbx_byte(linear_dst_format)));
-}
-
-static bool
-formats_match(GLbitfield buffer_bit, struct intel_renderbuffer *src_irb,
-              struct intel_renderbuffer *dst_irb)
-{
-   /* Note: don't just check gl_renderbuffer::Format, because in some cases
-    * multiple gl_formats resolve to the same native type in the miptree (for
-    * example MESA_FORMAT_Z24_UNORM_X8_UINT and MESA_FORMAT_Z24_UNORM_S8_UINT), and we can blit
-    * between those formats.
-    */
-   mesa_format src_format = find_miptree(buffer_bit, src_irb)->format;
-   mesa_format dst_format = find_miptree(buffer_bit, dst_irb)->format;
-
-   return color_formats_match(src_format, dst_format);
-}
-
-static bool
 try_blorp_blit(struct brw_context *brw,
                GLfloat srcX0, GLfloat srcY0, GLfloat srcX1, GLfloat srcY1,
                GLfloat dstX0, GLfloat dstY0, GLfloat dstX1, GLfloat dstY1,
@@ -191,16 +145,13 @@ try_blorp_blit(struct brw_context *brw,
    /* Find buffers */
    struct intel_renderbuffer *src_irb;
    struct intel_renderbuffer *dst_irb;
+   struct intel_mipmap_tree *src_mt;
+   struct intel_mipmap_tree *dst_mt;
    switch (buffer_bit) {
    case GL_COLOR_BUFFER_BIT:
       src_irb = intel_renderbuffer(read_fb->_ColorReadBuffer);
       for (unsigned i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; ++i) {
          dst_irb = intel_renderbuffer(ctx->DrawBuffer->_ColorDrawBuffers[i]);
-         if (dst_irb && !formats_match(buffer_bit, src_irb, dst_irb))
-            return false;
-      }
-      for (unsigned i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; ++i) {
-         dst_irb = intel_renderbuffer(ctx->DrawBuffer->_ColorDrawBuffers[i]);
 	 if (dst_irb)
             do_blorp_blit(brw, buffer_bit, src_irb, dst_irb, srcX0, srcY0,
                           srcX1, srcY1, dstX0, dstY0, dstX1, dstY1,
@@ -212,8 +163,17 @@ try_blorp_blit(struct brw_context *brw,
          intel_renderbuffer(read_fb->Attachment[BUFFER_DEPTH].Renderbuffer);
       dst_irb =
          intel_renderbuffer(draw_fb->Attachment[BUFFER_DEPTH].Renderbuffer);
-      if (!formats_match(buffer_bit, src_irb, dst_irb))
+      src_mt = find_miptree(buffer_bit, src_irb);
+      dst_mt = find_miptree(buffer_bit, dst_irb);
+
+      /* We can't handle format conversions between Z24 and other formats
+       * since we have to lie about the surface format. See the comments in
+       * brw_blorp_surface_info::set().
+       */
+      if ((src_mt->format == MESA_FORMAT_Z24_UNORM_X8_UINT) !=
+          (dst_mt->format == MESA_FORMAT_Z24_UNORM_X8_UINT))
          return false;
+
       do_blorp_blit(brw, buffer_bit, src_irb, dst_irb, srcX0, srcY0,
                     srcX1, srcY1, dstX0, dstY0, dstX1, dstY1,
                     filter, mirror_x, mirror_y);
@@ -223,8 +183,6 @@ try_blorp_blit(struct brw_context *brw,
          intel_renderbuffer(read_fb->Attachment[BUFFER_STENCIL].Renderbuffer);
       dst_irb =
          intel_renderbuffer(draw_fb->Attachment[BUFFER_STENCIL].Renderbuffer);
-      if (!formats_match(buffer_bit, src_irb, dst_irb))
-         return false;
       do_blorp_blit(brw, buffer_bit, src_irb, dst_irb, srcX0, srcY0,
                     srcX1, srcY1, dstX0, dstY0, dstX1, dstY1,
                     filter, mirror_x, mirror_y);
-- 
1.9.3