i915g: Add comment about DDX/DDY.

diff --git a/src/gallium/drivers/i915/i915_fpc_translate.c b/src/gallium/drivers/i915/i915_fpc_translate.c
index 0cbd4f2..df606e2 100644 (file)
--- a/src/gallium/drivers/i915/i915_fpc_translate.c
+++ b/src/gallium/drivers/i915/i915_fpc_translate.c
@@ -450,6 +450,7 @@ emit_simple_arith_swap2(struct i915_fp_compile *p,
  *
  * Possible concerns:
  *
+ * DDX, DDY -- return 0
  * SIN, COS -- could use another taylor step?
  * LIT      -- results seem a little different to sw mesa
  * LOG      -- different to mesa on negative numbers, but this is conformant.