[Mesa-dev] [PATCH 2/2] i965: Disallow linear blits that are not cacheline aligned.

[Kenneth Graunke]

The BLT engine on Gen8+ requires linear surfaces to be cacheline
aligned.  This restriction was added as part of converting the BLT to
use 48-bit addressing.

The main user, intel_emit_linear_blit, now handles this properly.
But we might also have linear miptrees; just refuse to blit those.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88521
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/drivers/dri/i965/intel_blit.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_blit.c b/src/mesa/drivers/dri/i965/intel_blit.c
index 98d414c..7680a40 100644
--- a/src/mesa/drivers/dri/i965/intel_blit.c
+++ b/src/mesa/drivers/dri/i965/intel_blit.c
@@ -271,6 +271,20 @@ intel_miptree_blit(struct brw_context *brw,
    return true;
 }
 
+static bool
+alignment_valid(struct brw_context *brw, unsigned offset, uint32_t tiling)
+{
+   /* Tiled buffers must be page-aligned (4K). */
+   if (tiling != I915_TILING_NONE)
+      return (offset & 4095) == 0;
+
+   /* On Gen8+, linear buffers must be cacheline-aligned. */
+   if (brw->gen >= 8)
+      return (offset & 63) == 0;
+
+   return true;
+}
+
 /* Copy BitBlt
  */
 bool
@@ -296,14 +310,11 @@ intelEmitCopyBlit(struct brw_context *brw,
    bool dst_y_tiled = dst_tiling == I915_TILING_Y;
    bool src_y_tiled = src_tiling == I915_TILING_Y;
 
-   if (dst_tiling != I915_TILING_NONE) {
-      if (dst_offset & 4095)
-	 return false;
-   }
-   if (src_tiling != I915_TILING_NONE) {
-      if (src_offset & 4095)
-	 return false;
-   }
+   if (!alignment_valid(brw, dst_offset, dst_tiling))
+      return false;
+   if (!alignment_valid(brw, src_offset, src_tiling))
+      return false;
+
    if ((dst_y_tiled || src_y_tiled) && brw->gen < 6)
       return false;
 
-- 
2.3.5