linux-kernel - Re: [PATCH v2 2/3] coresight: cti: Add PM runtime call in enable

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Date:   Mon, 9 Jan 2023 16:47:12 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     James Clark <james.clark@....com>, coresight@...ts.linaro.org,
        quic_jinlmao@...cinc.com, mike.leach@...aro.org
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] coresight: cti: Add PM runtime call in
 enable_store

On 06/01/2023 15:23, James Clark wrote:
> From: Mao Jinlong <quic_jinlmao@...cinc.com>
> 
> In commit 6746eae4bbad ("coresight: cti: Fix hang in cti_disable_hw()")
> PM runtime calls are removed from cti_enable_hw/cti_disable_hw. When
> enabling CTI by writing enable sysfs node, clock for accessing CTI
> register won't be enabled. Device will crash due to register access
> issue. Add PM runtime call in enable_store to fix this issue.
> 
> Fixes: 6746eae4bbad ("coresight: cti: Fix hang in cti_disable_hw()")
> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
> [Change to only call pm_runtime_put if a disable happened]
> Signed-off-by: James Clark <james.clark@....com>
> ---
>   drivers/hwtracing/coresight/coresight-cti-sysfs.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> index 6d59c815ecf5..71e7a8266bb3 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> @@ -108,10 +108,19 @@ static ssize_t enable_store(struct device *dev,
>   	if (ret)
>   		return ret;
>   
> -	if (val)
> +	if (val) {
> +		ret = pm_runtime_resume_and_get(dev->parent);
> +		if (ret)
> +			return ret;
>   		ret = cti_enable(drvdata->csdev);
> -	else
> +		if (ret)
> +			pm_runtime_put(dev->parent);
> +	} else {
>   		ret = cti_disable(drvdata->csdev);
> +		if (!ret)
> +			pm_runtime_put(dev->parent);
> +	}
> +
>   	if (ret)
>   		return ret;
>   	return size;

Looks good to me.

@Mao Jinolong,

Are you able to test the patches 1 & 2 and confirm they solve your issue ?

Suzuki