[Intel-gfx] [PATCH v2] drm/i915: Add the predicate source registers to the register whitelist

[Neil Roberts]

The predicate source registers are needed to implement conditional
rendering without stalling. The two source registers are used to load
the previous values of the PS_DEPTH_COUNT register saved from
PIPE_CONTROL commands. These can then be compared and used to set the
predicate enable bit via the MI_PREDICATE command.

The command parser version number is increased to 2 to make it easier
to detect the new functionality in user space.

Signed-off-by: Neil Roberts <neil at linux.intel.com>
---

Here is a v2 of the patch that also updates the command parser version
to make it easier to detect whether we can use the register in Mesa.
I have posted a second version of the Mesa patch which uses this here:

http://lists.freedesktop.org/archives/mesa-dev/2014-November/070362.html

This was suggested by Glenn Kennard.

 drivers/gpu/drm/i915/i915_cmd_parser.c | 6 +++++-
 drivers/gpu/drm/i915/i915_reg.h        | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index 4c35e2a..3eb421e 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -408,6 +408,8 @@ static const u32 gen7_render_regs[] = {
 	REG64(PS_INVOCATION_COUNT),
 	REG64(PS_DEPTH_COUNT),
 	OACONTROL, /* Only allowed for LRI and SRM. See below. */
+	REG64(MI_PREDICATE_SRC0),
+	REG64(MI_PREDICATE_SRC1),
 	GEN7_3DPRIM_END_OFFSET,
 	GEN7_3DPRIM_START_VERTEX,
 	GEN7_3DPRIM_VERTEX_COUNT,
@@ -1054,6 +1056,8 @@ int i915_cmd_parser_get_version(void)
 	 *
 	 * 1. Initial version. Checks batches and reports violations, but leaves
 	 *    hardware parsing enabled (so does not allow new use cases).
+	 * 2. Allow access to the MI_PREDICATE_SRC0 and
+	 *    MI_PREDICATE_SRC1 registers.
 	 */
-	return 1;
+	return 2;
 }
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index ea84e1e..9275d41 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -314,6 +314,8 @@
 #define   MI_BATCH_GTT		    (2<<6) /* aliased with (1<<7) on gen4 */
 #define MI_BATCH_BUFFER_START_GEN8	MI_INSTR(0x31, 1)
 
+#define MI_PREDICATE_SRC0	(0x2400)
+#define MI_PREDICATE_SRC1	(0x2408)
 
 #define MI_PREDICATE_RESULT_2	(0x2214)
 #define  LOWER_SLICE_ENABLED	(1<<0)
-- 
1.9.3