Re: [PATCH v5 3/7] scsi: ufs: Fix up auto hibern8 enablement

Stanley Chu
2019-11-15T07:18:40Z

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