[Intel-gfx] [PATCH v2] drm/i915/gvt: Implement WaForceWakeRenderDuringMmioTLBInvalidate

[Arkadiusz Hiler]

When invalidating RCS TLB the device can enter RC6 state interrupting
the process, therefore the need for render forcewake for the whole
procedure.

This WA is needed for all production SKL SKUs.

v2: reworked putting and getting forcewake with help of Mika Kuoppala

References: HSD#2136899, HSD#1404391274
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
---
 drivers/gpu/drm/i915/gvt/render.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/render.c b/drivers/gpu/drm/i915/gvt/render.c
index feebb65..8e7a80e 100644
--- a/drivers/gpu/drm/i915/gvt/render.c
+++ b/drivers/gpu/drm/i915/gvt/render.c
@@ -118,6 +118,7 @@ static u32 gen9_render_mocs_L3[32];
 static void handle_tlb_pending_event(struct intel_vgpu *vgpu, int ring_id)
 {
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
+	enum forcewake_domains fw;
 	i915_reg_t reg;
 	u32 regs[] = {
 		[RCS] = 0x4260,
@@ -135,11 +136,25 @@ static void handle_tlb_pending_event(struct intel_vgpu *vgpu, int ring_id)
 
 	reg = _MMIO(regs[ring_id]);
 
+	/* WaForceWakeRenderDuringMmioTLBInvalidate:skl
+	 * we need to put a forcewake when invalidating RCS TLB caches,
+	 * otherwise device can go to RC6 state and interrupt invalidation
+	 * process
+	 */
+	fw = intel_uncore_forcewake_for_reg(dev_priv, reg,
+					    FW_REG_READ | FW_REG_WRITE);
+	if (ring_id == RCS && IS_SKYLAKE(dev_priv))
+		fw |= FORCEWAKE_RENDER;
+
+	intel_uncore_forcewake_get(dev_priv, fw);
+
 	I915_WRITE(reg, 0x1);
 
 	if (wait_for_atomic((I915_READ(reg) == 0), 50))
 		gvt_err("timeout in invalidate ring (%d) tlb\n", ring_id);
 
+	intel_uncore_forcewake_put(dev_priv, fw);
+
 	gvt_dbg_core("invalidate TLB for ring %d\n", ring_id);
 }
 
-- 
2.7.4