Re: [Intel-xe] [PATCH v2 26/30] drm/xe/tlb: Obtain forcewake when doing GGTT TLB invalidations

["Das, Nirmoy" <nirmoy.das@linux.intel.com>]

On 5/20/2023 1:18 AM, Matt Roper wrote:
> Updates to the GGTT can happen when there are no in-flight jobs keeping
> the hardware awake.  If the GT is powered down when invalidation is
> requested, we will not be able to communicate with the GuC (or MMIO) and
> the invalidation request will go missing.  Explicitly grab GT forcewake
> to ensure the GT and GuC are powered up during the TLB invalidation.
>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>

> ---
>   drivers/gpu/drm/xe/xe_ggtt.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
> index 31f958613c2f..8f8d0f6a82cd 100644
> --- a/drivers/gpu/drm/xe/xe_ggtt.c
> +++ b/drivers/gpu/drm/xe/xe_ggtt.c
> @@ -193,6 +193,13 @@ static void ggtt_invalidate_gt_tlb(struct xe_gt *gt)
>   	if (!gt)
>   		return;
>   
> +	/*
> +	 * Invalidation can happen when there's no in-flight work keeping the
> +	 * GT awake.  We need to explicitly grab forcewake to ensure the GT
> +	 * and GuC are accessible.
> +	 */
> +	xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
> +
>   	/* TODO: vfunc for GuC vs. non-GuC */
>   
>   	if (gt->uc.guc.submission_state.enabled) {
> @@ -214,6 +221,8 @@ static void ggtt_invalidate_gt_tlb(struct xe_gt *gt)
>   			xe_mmio_write32(gt, GUC_TLB_INV_CR,
>   					GUC_TLB_INV_CR_INVALIDATE);
>   	}
> +
> +	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
>   }
>   
>   void xe_ggtt_invalidate(struct xe_ggtt *ggtt)