Mesa (master): svga: fix a texture readback bug

[Brian Paul]

Module: Mesa
Branch: master
Commit: ec16a5b0915a4a764e077f2b6abc8723143e488d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ec16a5b0915a4a764e077f2b6abc8723143e488d

Author: Brian Paul <brianp at vmware.com>
Date:   Fri Aug 26 16:25:39 2016 -0600

svga: fix a texture readback bug

Backing views/surfaces are used to handle the case when a resource is
bound both as a render target and as a sampler source (such as when
doing auto mipmap generation).

This patch fixes a bug where mapping a resource (to do a glReadPixels)
was reading the stale data in the original surface rather than the
backing surface which was rendered to.

We need to propagate the backing resource (which we rendered to) back
to the original resource before we read from it.  The problem was the
svga_propagate_rendertargets() function was examining the wrong surface
views.

This fixes the "poc9" test described in VMware bug 1686661.
Also tested with Piglit, Cinebench, Lightsmark, etc.

Reviewed-by: Charmaine Lee <charmainel at vmware.com>

---

 src/gallium/drivers/svga/svga_context.c |  2 ++
 src/gallium/drivers/svga/svga_surface.c | 16 ++++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/gallium/drivers/svga/svga_context.c b/src/gallium/drivers/svga/svga_context.c
index b3b2728..78fb558 100644
--- a/src/gallium/drivers/svga/svga_context.c
+++ b/src/gallium/drivers/svga/svga_context.c
@@ -229,6 +229,8 @@ struct pipe_context *svga_context_create(struct pipe_screen *screen,
    memset(svga->state.hw_draw.sampler_views, 0,
           sizeof(svga->state.hw_draw.sampler_views));
    svga->state.hw_draw.num_views = 0;
+   svga->state.hw_draw.num_rendertargets = 0;
+   svga->state.hw_draw.dsv = NULL;
 
    /* Initialize the shader pointers */
    svga->state.hw_draw.vs = NULL;
diff --git a/src/gallium/drivers/svga/svga_surface.c b/src/gallium/drivers/svga/svga_surface.c
index 75e76fb..f6a7913 100644
--- a/src/gallium/drivers/svga/svga_surface.c
+++ b/src/gallium/drivers/svga/svga_surface.c
@@ -664,17 +664,21 @@ svga_propagate_surface(struct svga_context *svga, struct pipe_surface *surf)
 void
 svga_propagate_rendertargets(struct svga_context *svga)
 {
-   const unsigned num_cbufs = svga_screen(svga->pipe.screen)->max_color_buffers;
    unsigned i;
 
-   for (i = 0; i < num_cbufs; i++) {
-      if (svga->curr.framebuffer.cbufs[i]) {
-         svga_propagate_surface(svga, svga->curr.framebuffer.cbufs[i]);
+   /* Note that we examine the svga->state.hw_draw.framebuffer surfaces,
+    * not the svga->curr.framebuffer surfaces, because it's the former
+    * surfaces which may be backing surface views (the actual render targets).
+    */
+   for (i = 0; i < svga->state.hw_draw.num_rendertargets; i++) {
+      struct pipe_surface *s = svga->state.hw_draw.rtv[i];
+      if (s) {
+         svga_propagate_surface(svga, s);
       }
    }
 
-   if (svga->curr.framebuffer.zsbuf) {
-      svga_propagate_surface(svga, svga->curr.framebuffer.zsbuf);
+   if (svga->state.hw_draw.dsv) {
+      svga_propagate_surface(svga, svga->state.hw_draw.dsv);
    }
 }