While it is preferrable to use a fast manual detiling method for LLC
(does not require synchronisation with a busy GPU and for accessing main
memory both the CPU and GPU have the same bandwidth), if we don't have
such a path then using the GPU to perform the blit is far preferable to
a coherent mmapping.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
src/mesa/drivers/dri/i965/intel_pixel_read.c | 117 +++++++++++++++++++++++++++
1 file changed, 117 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/intel_pixel_read.c
b/src/mesa/drivers/dri/i965/intel_pixel_read.c
index 5765027..16a04fb 100644
--- a/src/mesa/drivers/dri/i965/intel_pixel_read.c
+++ b/src/mesa/drivers/dri/i965/intel_pixel_read.c
@@ -196,6 +196,118 @@ intel_readpixels_tiled_memcpy(struct gl_context * ctx,
);
}
+static bool
+intel_readpixels_userptr(struct gl_context * ctx,
+ GLint x, GLint y,
+ GLsizei width, GLsizei height,
+ GLenum format, GLenum type,
+ GLvoid * pixels,
+ const struct gl_pixelstore_attrib *pack)
+{
+ struct brw_context *brw = brw_context(ctx);
+
+ if (_mesa_is_bufferobj(pack->BufferObj))
+ return false;
+
+ struct gl_renderbuffer *rb = NULL;
+ switch (format) {
+ case GL_STENCIL_INDEX:
+ if (0) /* Stencils are W-tiled which is not supported by the blitter */
+ rb = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
+ break;
+ case GL_DEPTH_COMPONENT:
+ rb = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
+ break;
+ case GL_DEPTH_STENCIL_EXT:
+ break;
+ default:
+ /* all other formats should be color formats */
+ rb = ctx->ReadBuffer->_ColorReadBuffer;
+ break;
+ }
+ if (rb == NULL)
+ return false;
+
+ if (pack->SwapBytes || pack->LsbFirst) {
+ DBG("%s: bad packing params\n", __func__);
+ return false;
+ }
+
+ if (_mesa_readpixels_needs_slow_path(ctx, format, type, GL_TRUE)) {
+ DBG("%s: non-trivial conversion required\n", __func__);
+ return false;
+ }
+
+ struct intel_renderbuffer *irb = intel_renderbuffer(rb);
+ struct intel_mipmap_tree *src = irb->mt;
+ if (format == GL_STENCIL_INDEX && src->stencil_mt)
+ src = src->stencil_mt;
+
+ if (!_mesa_format_matches_format_and_type(src->format, format, type, 0)) {
+ mesa_format src_format = src->format;
+ mesa_format dst_format = _mesa_format_from_format_and_type(format, type);
+ if (_mesa_format_is_mesa_array_format(dst_format))
+ dst_format = _mesa_format_from_array_format(dst_format);
+
+ /* We can safely discard sRGB for the ReadPixels interface */
+ src_format = _mesa_get_srgb_format_linear(src_format);
+ dst_format = _mesa_get_srgb_format_linear(dst_format);
+
+ if (!intel_miptree_blit_compatible_formats(src_format, dst_format)) {
+ DBG("%s: incompatible formats for blit (src=%s, dst=%s)\n",
+ __func__,
+ _mesa_get_format_name(src_format),
+ _mesa_get_format_name(dst_format));
+ return false;
+ }
+ }
+
+ bool dst_flip = false;
+ int dst_stride = _mesa_image_row_stride(pack, width, format, type);
+ int size = dst_stride * height;
+
+ if (pack->Invert) {
+ dst_stride = -dst_stride;
+ dst_flip = true;
+ }
+
+ int dst_offset = (GLintptr)pixels & 4095;
+ dst_offset += _mesa_image_offset(2, pack, width, height,
+ format, type, 0, 0, 0);
+ size += dst_offset;
+ size = ALIGN(size, 4096);
+
+ brw_bo *dst_buffer =
+ brw_bo_create_userptr(&brw->batch, "readpixels",
+ (void *)((GLintptr)pixels & ~4095),
+ size, 0);
+ if (dst_buffer == NULL)
+ return false;
+
+ bool ok = false;
+ struct intel_mipmap_tree *dst =
+ intel_miptree_create_for_bo(brw,
+ dst_buffer,
+ src->format,
+ dst_offset,
+ width, height, 1,
+ dst_stride,
+ 0);
+ if (dst)
+ ok = intel_miptree_blit(brw,
+ src, irb->mt_level, irb->mt_layer,
+ x, y, false,
+ dst, 0, 0,
+ 0, 0, dst_flip,
+ width, height, GL_COPY);
+ intel_miptree_release(&dst);
+
+ brw_bo_map(dst_buffer, MAP_WRITE, PERF_DEBUG(brw, "ReadPixels"));
+ brw_bo_put(dst_buffer);
+
+ return ok;
+}
+
void
intelReadPixels(struct gl_context * ctx,
GLint x, GLint y, GLsizei width, GLsizei height,
@@ -244,6 +356,11 @@ intelReadPixels(struct gl_context * ctx,
if(ok)
return;
+ ok = intel_readpixels_userptr(ctx, x, y, width, height,
+ format, type, pixels, pack);
+ if(ok)
+ return;
+
/* glReadPixels() wont dirty the front buffer, so reset the dirty
* flag after calling intel_prepare_render(). */
dirty = brw->front_buffer_dirty;
--
2.5.0
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