Re: [PATCH v2 2/2] drm/xe/vf: Retry sending MMIO request to GUC on timeout error

["Piotr Piórkowski" <piotr.piorkowski@intel.com>]

Satyanarayana K V P <satyanarayana.k.v.p@intel.com> wrote on pią [2025-lut-21 11:27:22 +0530]:
> Add support to allow retrying the sending of MMIO requests
> from the VF to the GUC in the event of an error. During the
> suspend/resume process, VFs begin resuming only after the PF has
> resumed. Although the PF resumes, the GUC reset and provisioning
> occur later in a separate worker process.
> 
> When there are a large number of VFs, some may attempt to resume
> before the PF has completed its provisioning. Therefore, if a
> MMIO request from a VF fails during this period, we will retry
> sending the request up to GUC_RESET_VF_STATE_RETRY_MAX times,
> which is set to a maximum of 10 attempts.
> 
> Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
> Cc: Michał Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Michał Winiarski <michal.winiarski@intel.com>
> Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> index 4831549da319..a439261bf4d7 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> @@ -47,12 +47,19 @@ static int guc_action_vf_reset(struct xe_guc *guc)
>  	return ret > 0 ? -EPROTO : ret;
>  }
>  
> +#define GUC_RESET_VF_STATE_RETRY_MAX	10
>  static int vf_reset_guc_state(struct xe_gt *gt)
>  {
> +	unsigned int retry = GUC_RESET_VF_STATE_RETRY_MAX;
>  	struct xe_guc *guc = &gt->uc.guc;
>  	int err;
>  
> -	err = guc_action_vf_reset(guc);
> +	do {
> +		err = guc_action_vf_reset(guc);
> +		if (!err || err != -ETIMEDOUT)
> +			break;
> +	} while (--retry);
> +

LGTM:
Reviewed-by: Piotr Piorkowski <piotr.piorkowski@intel.com>
>  	if (unlikely(err))
>  		xe_gt_sriov_err(gt, "Failed to reset GuC state (%pe)\n", ERR_PTR(err));
>  	return err;
> -- 
> 2.35.3
> 

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