linux-kernel - Re: [PATCH] remoteproc: xlnx: avoid RPU force power down

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Message-ID: <aAe80OlwWENHI2I9@p14s>
Date: Tue, 22 Apr 2025 09:59:12 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Tanmay Shah <tanmay.shah@....com>
Cc: andersson@...nel.org, linux-remoteproc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] remoteproc: xlnx: avoid RPU force power down

Good morning,

On Mon, Apr 14, 2025 at 11:46:01AM -0700, Tanmay Shah wrote:
> Powering off RPU using force_pwrdwn call results in system failure
> if there are multiple users of that RPU node. Better mechanism is to use
> request_node and release_node EEMI calls. With use of these EEMI calls,
> platform management controller will take-care of powering off RPU
> when there is no user.
> 
> Signed-off-by: Tanmay Shah <tanmay.shah@....com>
> ---
>  drivers/remoteproc/xlnx_r5_remoteproc.c | 29 ++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c b/drivers/remoteproc/xlnx_r5_remoteproc.c
> index 5aeedeaf3c41..3597359c0fc8 100644
> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c
> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
> @@ -380,6 +380,18 @@ static int zynqmp_r5_rproc_start(struct rproc *rproc)
>  	dev_dbg(r5_core->dev, "RPU boot addr 0x%llx from %s.", rproc->bootaddr,
>  		bootmem == PM_RPU_BOOTMEM_HIVEC ? "OCM" : "TCM");
>  
> +	/* Request node before starting RPU core if new version of API is supported */
> +	if (zynqmp_pm_feature(PM_REQUEST_NODE) > 1) {
> +		ret = zynqmp_pm_request_node(r5_core->pm_domain_id,
> +					     ZYNQMP_PM_CAPABILITY_ACCESS, 0,
> +					     ZYNQMP_PM_REQUEST_ACK_BLOCKING);
> +		if (ret < 0) {
> +			dev_err(r5_core->dev, "failed to request 0x%x",
> +				r5_core->pm_domain_id);
> +			return ret;
> +		}
> +	}
> +
>  	ret = zynqmp_pm_request_wake(r5_core->pm_domain_id, 1,
>  				     bootmem, ZYNQMP_PM_REQUEST_ACK_NO);
>  	if (ret)
> @@ -401,10 +413,25 @@ static int zynqmp_r5_rproc_stop(struct rproc *rproc)
>  	struct zynqmp_r5_core *r5_core = rproc->priv;
>  	int ret;
>  
> +	/* Use release node API to stop core if new version of API is supported */
> +	if (zynqmp_pm_feature(PM_RELEASE_NODE) > 1) {
> +		ret = zynqmp_pm_release_node(r5_core->pm_domain_id);
> +		if (ret)
> +			dev_err(r5_core->dev, "failed to stop remoteproc RPU %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (zynqmp_pm_feature(PM_FORCE_POWERDOWN) < 1) {
> +		dev_dbg(r5_core->dev, "EEMI interface %d not supported\n",
> +			PM_FORCE_POWERDOWN);
> +		return -EOPNOTSUPP;
> +	}

Here I have to guess, because it is not documented, that it is the check to see
if zynqmp_pm_force_pwrdwn() is available.  I'm not sure why it is needed because
zynqmp_pm_force_pwrdwn() returns and error code. 

Thanks,
Mathieu

> +
> +	/* maintain force pwr down for backward compatibility */
>  	ret = zynqmp_pm_force_pwrdwn(r5_core->pm_domain_id,
>  				     ZYNQMP_PM_REQUEST_ACK_BLOCKING);
>  	if (ret)
> -		dev_err(r5_core->dev, "failed to stop remoteproc RPU %d\n", ret);
> +		dev_err(r5_core->dev, "core force power down failed\n");
>  
>  	return ret;
>  }
> 
> base-commit: 8532691d0a85ab2a826808207e904f7d62a9d804
> -- 
> 2.34.1
>