[PATCH] drm/radeon: update ib_execute for SI

[alexdeucher at gmail.com]

From: Alex Deucher <alexander.deucher at amd.com>

When submitting a CONST_IB, emit a SWITCH_BUFFER
packet before the CONST_IB.  This isn't strictly necessary
(the driver will work fine without it), but is good practice
and allows for more flexible DE/CE sychronization options
in the future.  Current userspace drivers do not take
advantage of the CE yet.

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/radeon/si.c  |    6 ++++++
 drivers/gpu/drm/radeon/sid.h |    1 +
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index 53e313b..191a3cd 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -1778,6 +1778,12 @@ void si_ring_ib_execute(struct radeon_device *rdev, struct radeon_ib *ib)
 	else
 		header = PACKET3(PACKET3_INDIRECT_BUFFER, 2);
 
+	if (ib->is_const_ib) {
+		/* set switch buffer packet before const IB */
+		radeon_ring_write(ring, PACKET3(PACKET3_SWITCH_BUFFER, 0));
+		radeon_ring_write(ring, 0);
+	}
+
 	radeon_ring_write(ring, header);
 	radeon_ring_write(ring,
 #ifdef __BIG_ENDIAN
diff --git a/drivers/gpu/drm/radeon/sid.h b/drivers/gpu/drm/radeon/sid.h
index db40679..7869089 100644
--- a/drivers/gpu/drm/radeon/sid.h
+++ b/drivers/gpu/drm/radeon/sid.h
@@ -901,5 +901,6 @@
 #define	PACKET3_WAIT_ON_DE_COUNTER_DIFF			0x88
 #define	PACKET3_SET_CE_DE_COUNTERS			0x89
 #define	PACKET3_WAIT_ON_AVAIL_BUFFER			0x8A
+#define	PACKET3_SWITCH_BUFFER				0x8B
 
 #endif
-- 
1.7.7.5