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From: Stanley Chu <stanley.chu@mediatek.com>
To: Can Guo <cang@codeaurora.org>
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
Date: Fri, 15 Nov 2019 15:18:31 +0800
Message-ID: <1573802311.4956.8.camel@mtkswgap22> (raw)
In-Reply-To: <2a925548b8ead7c3b5ddf2d7bf3de05d@codeaurora.org>

Hi Can,

On Fri, 2019-11-15 at 15:03 +0800, Can Guo wrote:
> 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 for explanation.

I fully understand the intention of this patch.

Just wonder if "if (!pm_runtime_suspended(hba->dev))" could be removed
and then always do pm_runtime_get_sync() here.

This could avoid possible racing and enable AH8 regardless of current
runtime status.

> Thanks,
> Can Guo.

Thanks,
Stanley


  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-15  6:09 [PATCH v5 0/7] UFS driver general fixes bundle 3 Can Guo
2019-11-15  6:09 ` [PATCH v5 1/7] scsi: ufs: Add device reset in link recovery path Can Guo
2019-11-15  6:25   ` Stanley Chu
2019-11-15  6:09 ` [PATCH v5 2/7] scsi: ufs-qcom: Add reset control support for host controller Can Guo
2019-11-15 10:08   ` Avri Altman
2019-12-16 19:04   ` Vinod Koul
2019-12-16 19:12     ` Jeffrey Hugo
2019-12-17  0:37       ` cang
2019-12-17  4:13         ` Vinod Koul
2019-12-17  7:10           ` cang
2019-12-17  9:24             ` Vinod Koul
2019-12-17 10:09               ` cang
2019-12-17 15:08                 ` Vinod Koul
2019-12-17 16:00                   ` Jeffrey Hugo
2019-12-17 18:44                     ` cang
2019-12-18  4:12                       ` Vinod Koul
2019-12-19  7:12                         ` cang
2019-12-19 14:21                           ` Vinod Koul
2019-12-19 14:25                             ` Jeffrey Hugo
2019-12-19 14:52                               ` Vinod Koul
2019-12-20  0:30                                 ` cang
2019-11-15  6:09 ` [PATCH v5 3/7] scsi: ufs: Fix up auto hibern8 enablement Can Guo
2019-11-15  6:35   ` Stanley Chu
2019-11-15  7:03     ` Can Guo
2019-11-15  7:18       ` Stanley Chu [this message]
2019-11-15 12:27         ` Can Guo
2019-11-15 13:46           ` Stanley Chu
2019-11-15  6:09 ` [PATCH v5 4/7] scsi: ufs: Fix register dump caused sleep in atomic context Can Guo
2019-11-15  6:09 ` [PATCH v5 5/7] scsi: ufs: Fix irq return code Can Guo
2019-11-15  6:09 ` [PATCH v5 6/7] scsi: ufs: Abort gating if clock on request is pending Can Guo
2019-11-15  6:09 ` [PATCH v5 7/7] scsi: ufs: Fix error handing during hibern8 enter Can Guo
2019-11-15 10:12   ` Avri Altman
2019-11-17 16:36   ` [EXT] " Bean Huo (beanhuo)
2019-11-19  4:28 ` [PATCH v5 0/7] UFS driver general fixes bundle 3 Martin K. Petersen

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