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

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Message-ID: <072f2139-a860-406b-96b8-aa59a83950ee@amd.com>
Date: Tue, 22 Apr 2025 11:10:47 -0500
From: Tanmay Shah <tanmay.shah@....com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: andersson@...nel.org, linux-remoteproc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] remoteproc: xlnx: avoid RPU force power down



On 4/22/25 10:59 AM, Mathieu Poirier wrote:
> 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.
> 
Hello,

Thanks for reviews. Yes you are correct. Actually instead, the check 
should be for version 1 of PM_FORCE_POWER_DOWN. If version 1 is 
supported, only then execute the call otherwise print the error.
Hence, the check should be something like:

if (zynqmp_pm_feature(PM_FORCE_POWERDOWN) != 1) {
	error out.
}

I will fix and add comment as well.

> 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
>>