Arkadiusz Hiler <arkadiusz.hiler@xxxxxxxxx> writes:
> 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@xxxxxxxxx>
> Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
> Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@xxxxxxxxx>
> ---
> 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);
>
To take full advantage of the explicit forcewake dance, please
look at I915_WRITE_FW and I915_READ_FW.
-Mika
> 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
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