radeon/llvm: Add some comments

1 files changed, 7 insertions, 2 deletions

diff --git a/src/gallium/drivers/radeon/SIAssignInterpRegs.cpp b/src/gallium/drivers/radeon/SIAssignInterpRegs.cpp
index b0bdf701a74..1ef097f7b1e 100644
--- a/src/gallium/drivers/radeon/SIAssignInterpRegs.cpp
+++ b/src/gallium/drivers/radeon/SIAssignInterpRegs.cpp
@@ -1,4 +1,4 @@
-//===-- SIAssignInterpRegs.cpp - TODO: Add brief description -------===//
+//===-- SIAssignInterpRegs.cpp - Assign interpolation registers -----------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,7 +7,12 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// TODO: Add full description
+// This pass maps the pseudo interpolation registers to the correct physical
+// registers.  Prior to executing a fragment shader, the GPU loads interpolation
+// parameters into physical registers.  The specific physical register that each
+// interpolation parameter ends up in depends on the type of the interpolation
+// parameter as well as how many interpolation parameters are used by the
+// shader.
 //
 //===----------------------------------------------------------------------===//