Hi Can,
On Tue, 2020-10-20 at 10:35 +0800, Can Guo wrote:
> Hi Stanley,
>
> On 2020-09-22 15:09, Can Guo wrote:
> > If someone plays with the UFS clk scaling devfreq governor through
> > sysfs,
> > ufshcd_devfreq_scale may be called even when hba is not runtime ACTIVE,
> > which can lead to unexpected error. We cannot just protect it by
> > calling
> > pm_runtime_get_sync, because that may cause racing problem since hba
> > runtime suspend ops needs to suspend clk scaling. In order to fix it,
> > call
> > pm_runtime_get_noresume and check hba's runtime status, then only
> > proceed
> > if hba is runtime ACTIVE, otherwise just bail.
> >
> > governor_store
> > devfreq_performance_handler
> > update_devfreq
> > devfreq_set_target
> > ufshcd_devfreq_target
> > ufshcd_devfreq_scale
> >
> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index e4cb994..847f355 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -1294,8 +1294,15 @@ static int ufshcd_devfreq_target(struct device
> > *dev,
> > }
> > spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
> >
> > + pm_runtime_get_noresume(hba->dev);
> > + if (!pm_runtime_active(hba->dev)) {
> > + pm_runtime_put_noidle(hba->dev);
> > + ret = -EAGAIN;
> > + goto out;
> > + }
> > start = ktime_get();
> > ret = ufshcd_devfreq_scale(hba, scale_up);
> > + pm_runtime_put(hba->dev);
> >
> > trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
> > (scale_up ? "up" : "down"),
>
> Could you please review this one since we may be the only two
> users of clk scaling?
>
Looks good to me.
Reviewed-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
