[PATCH] drm/i915/gvt: Reduce rcs mocs switch latency

[Wang, Zhi A]

LGTM.

BTW: You can also remove forcewake get/put in handle_tlb_pending_event(). It's not in the hot path but it looks ugly...

Thanks,
Zhi.

-----Original Message-----
From: intel-gvt-dev [mailto:intel-gvt-dev-bounces at lists.freedesktop.org] On Behalf Of changbin.du at intel.com
Sent: Monday, October 30, 2017 8:19 AM
To: intel-gvt-dev at lists.freedesktop.org
Cc: Du, Changbin <changbin.du at intel.com>
Subject: [PATCH] drm/i915/gvt: Reduce rcs mocs switch latency

From: Changbin Du <changbin.du at intel.com>

Use I915_WRITE_FW instead of I915_WRITE to reduce overhead.
The overall mmio switch latency lowers from ~600us to ~180us.

Signed-off-by: Changbin Du <changbin.du at intel.com>
---
 drivers/gpu/drm/i915/gvt/render.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gvt/render.c b/drivers/gpu/drm/i915/gvt/render.c
index e16c355..0672178 100644
--- a/drivers/gpu/drm/i915/gvt/render.c
+++ b/drivers/gpu/drm/i915/gvt/render.c
@@ -209,7 +209,7 @@ static void load_mocs(struct intel_vgpu *vgpu, int ring_id)
 	offset.reg = regs[ring_id];
 	for (i = 0; i < 64; i++) {
 		gen9_render_mocs[ring_id][i] = I915_READ_FW(offset);
-		I915_WRITE(offset, vgpu_vreg(vgpu, offset));
+		I915_WRITE_FW(offset, vgpu_vreg(vgpu, offset));
 		offset.reg += 4;
 	}
 
-- 
2.7.4

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