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

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Message-ID: <6f89794a-ce14-439a-ce10-55ed175a10fe@arm.com>
Date:   Tue, 10 Jan 2023 11:08:50 +0000
From:   James Clark <james.clark@....com>
To:     Jinlong Mao <quic_jinlmao@...cinc.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        coresight@...ts.linaro.org, 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 10/01/2023 05:56, Jinlong Mao wrote:
> 
> On 1/10/2023 12:47 AM, Suzuki K Poulose wrote:
>> 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 ?
> 
> Hi Suzuki,
> 
> Tested from my side. Patch 1 & 2 can solve the issue when enable CTI by
> writing 1 to enable sysfs node.

Thanks, I added your tested-by tag on patches 1 + 2.