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Date:   Fri, 15 Nov 2019 15:03:37 +0800
From:   Can Guo <cang@codeaurora.org>
To:     Stanley Chu <stanley.chu@mediatek.com>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        rnayak@codeaurora.org, linux-scsi@vger.kernel.org,
        kernel-team@android.com, saravanak@google.com, salyzyn@google.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Bean Huo <beanhuo@micron.com>,
        Tomas Winkler <tomas.winkler@intel.com>,
        Venkat Gopalakrishnan <venkatg@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 3/7] scsi: ufs: Fix up auto hibern8 enablement
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 <1573798172-20534-4-git-send-email-cang@codeaurora.org>
 <1573799728.4956.5.camel@mtkswgap22>
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On 2019-11-15 14:35, Stanley Chu wrote:
> Hi Can,
> 
> On Thu, 2019-11-14 at 22:09 -0800, Can Guo wrote:
>> +	if (hba->ahit != ahit)
>> +		hba->ahit = ahit;
>>  	spin_unlock_irqrestore(hba->host->host_lock, flags);
>> +	if (!pm_runtime_suspended(hba->dev)) {
> 
> Always do pm_runtime_get_sync() here could avoid possible racing?
> 
> And thus AH8 could be enabled regardless of runtime status.
> 
>> +		pm_runtime_get_sync(hba->dev);
>> +		ufshcd_hold(hba, false);
>> +		ufshcd_auto_hibern8_enable(hba);
>> +		ufshcd_release(hba);
>> +		pm_runtime_put(hba->dev);
>> +	}
>>  }
> 
> Thanks,
> Stanley

Hi Stanley,

if !pm_runtime_suspended() is true, hba->dev's runtime status, other 
than RPM_ACTIVE,
may be RPM_SUSPENDING or RPM_RESUMING. So, here for safty, do 
pm_runtime_get_sync() once
before access registers, in case we hit corner cases in which powers 
and/or clocks are OFF.

Thanks,
Can Guo.