r300g: fix some bugs with zbuffer compression (v4)

This drops the memblock manager for ZMASK. Instead, only one zbuffer can be
compressed at a time. Note that this does not necessarily have to be slower.
When there is a large number of zbuffers, compression might be used more often
than it was before. It's also easier to debug.

How it works:
1) 'clear' turns the compression on.
2) If some other zbuffer is set or the currently-bound zbuffer is used
   for texturing, the driver decompresses it and then turns the compression off.

Notes:
- The ZMASK clear has been refactored, so that only one packet3 is used to clear
  ZMASK.
- The 8x8 compression mode is disabled. I couldn't make it work without issues.
- Also removed driver-specific stuff from u_blitter.

Driver status:
- RV530 and R580 appear to just work (finally).
- RV570 should work, but there may be an issue that we don't correctly
  calculate the number of dwords to clear, resulting in a partially
  uninitialized zbuffer.
- RS690 misrenders as if no ZMASK clear happened. No idea what's going on.
- RV350 may even hardlock. This issue was already present and this patch doesn't
  fix it.

I think we are still missing some hardware info we need to make the zbuffer
compression work fully.

Note that there is also an issue with HiZ, resulting in a sort of blocky
zigzagged corruption around some objects.

1 files changed, 26 insertions, 2 deletions

diff --git a/src/gallium/drivers/r300/r300_state_derived.c b/src/gallium/drivers/r300/r300_state_derived.c
index 95be7849f8..de4c271328 100644
--- a/src/gallium/drivers/r300/r300_state_derived.c
+++ b/src/gallium/drivers/r300/r300_state_derived.c
@@ -862,11 +862,35 @@ static void r300_merge_textures_and_samplers(struct r300_context* r300)
     }
 }
 
-void r300_update_derived_state(struct r300_context* r300)
+static void r300_decompress_depth_textures(struct r300_context *r300)
 {
-    r300_flush_depth_textures(r300);
+    struct r300_textures_state *state =
+        (struct r300_textures_state*)r300->textures_state.state;
+    struct pipe_resource *tex;
+    unsigned count = MIN2(state->sampler_view_count,
+                          state->sampler_state_count);
+    unsigned i;
+
+    if (!r300->zmask_locked || !r300->locked_zbuffer) {
+        return;
+    }
+
+    for (i = 0; i < count; i++) {
+        if (state->sampler_views[i] && state->sampler_states[i]) {
+            tex = state->sampler_views[i]->base.texture;
 
+            if (tex == r300->locked_zbuffer->texture) {
+                r300_decompress_zmask_locked(r300);
+                return;
+            }
+        }
+    }
+}
+
+void r300_update_derived_state(struct r300_context* r300)
+{
     if (r300->textures_state.dirty) {
+        r300_decompress_depth_textures(r300);
         r300_merge_textures_and_samplers(r300);
     }