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
Date: Fri, 15 Nov 2019 20:27:18 +0800 [thread overview]
Message-ID: <433afef33c8ca61aa299fa453c0d25d3@codeaurora.org> (raw)
In-Reply-To: <1573802311.4956.8.camel@mtkswgap22>
On 2019-11-15 15:18, Stanley Chu wrote:
> 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
Hi Stanley,
Actually, I thought about the way you reommand.
But I guess the author's intention here is to update the AH8 timer
only when current runtime status is RPM_ACTIVE. If it is not RPM_ACTIVE,
we just update the hba->ahit and bail out, because the AH8 timer will be
updated in ufshcd_reusme() eventually when hba is resumed. This can
avoid
frequently waking up hba just for accessing a single register.
How do you think?
Thanks,
Can Guo.
next prev parent reply other threads:[~2019-11-15 12:27 UTC|newest]
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
2019-11-15 12:27 ` Can Guo [this message]
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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