Am 06.09.2013 23:00, schrieb Alex Deucher:
This aligns the gfx, compute, and dma IBs to 8 DW boundries.
This aligns the the IB to the fetch size of the CP for optimal
performance. Additionally, r6xx hardware requires at least 4
DW alignment to avoid a hw bug.  This also aligns the DMA
IBs to 8 DW which is required for the DMA engine.  This
alignment is already handled in the gallium driver, but that
patch can be removed not that it's done in the winsys.

Signed-off-by: Alex Deucher <[email protected]>

I'm not 100% sure we should do this in the winsys, what's the benefit of doing it like this?

On the other hand UVD needs a similar padding to 16DW, see flush in radeon_uvd.c.

Christian.

---
  src/gallium/winsys/radeon/drm/radeon_drm_cs.c | 30 +++++++++++++++++++++++++++
  1 file changed, 30 insertions(+)

diff --git a/src/gallium/winsys/radeon/drm/radeon_drm_cs.c 
b/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
index 8c91906..e4128bc 100644
--- a/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
+++ b/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
@@ -470,6 +470,36 @@ static void radeon_drm_cs_flush(struct radeon_winsys_cs 
*rcs, unsigned flags, ui
      struct radeon_drm_cs *cs = radeon_drm_cs(rcs);
      struct radeon_cs_context *tmp;
+ switch (cs->base.ring_type) {
+    case RING_DMA:
+           /* pad DMA ring to 8 DWs */
+           if (cs->ws->info.chip_class <= SI) {
+                   while (rcs->cdw & 7)
+                           OUT_CS(&cs->base, 0xf0000000); /* NOP packet */
+           } else {
+                   while (rcs->cdw & 7)
+                           OUT_CS(&cs->base, 0x00000000); /* NOP packet */
+           }
+           break;
+    case RING_GFX:
+           /* pad DMA ring to 8 DWs to meet CP fetch alignment requirements
+            * r6xx, requires at least 4 dw alignment to avoid a hw bug.
+            */
+            if (flags & RADEON_FLUSH_COMPUTE) {
+                   if (cs->ws->info.chip_class <= SI) {
+                           while (rcs->cdw & 7)
+                                   OUT_CS(&cs->base, 0x80000000); /* type2 nop 
packet */
+                   } else {
+                           while (rcs->cdw & 7)
+                                   OUT_CS(&cs->base, 0xffff1000); /* type3 nop 
packet */
+                   }
+           } else {
+                   while (rcs->cdw & 7)
+                           OUT_CS(&cs->base, 0x80000000); /* type2 nop packet 
*/
+           }
+           break;
+    }
+
      if (rcs->cdw > RADEON_MAX_CMDBUF_DWORDS) {
         fprintf(stderr, "radeon: command stream overflowed\n");
      }

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