Re: [PATCH v4 7/7] scsi: ufs: Fix error handing during hibern8 enter

[Can Guo]

On 2019-11-14 19:06, Avri Altman wrote:
> > From: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> >
> > During clock gating (ufshcd_gate_work()), we first put the link 
> > hibern8 by
> > calling ufshcd_uic_hibern8_enter() and if ufshcd_uic_hibern8_enter() 
> > returns
> > success (0) then we gate all the clocks.
> > Now letâs zoom in to what ufshcd_uic_hibern8_enter() does internally:
> > It calls __ufshcd_uic_hibern8_enter() which on detecting the 
> > LINERESET,
> > initiates the full recovery and puts the link back to highest HS gear 
> > and returns
> > success (0) to ufshcd_uic_hibern8_enter() which is the issue as link 
> > is still in
> > active state due to recovery!
> > Now ufshcd_uic_hibern8_enter() returns success to ufshcd_gate_work() 
> > and
> > hence it goes ahead with gating the UFS clock while link is still in 
> > active state
> > hence I believe controller would raise UIC error interrupts. But when 
> > we service
> > the interrupt, clocks might have already been disabled!
> >
> > This change fixes for this by returning failure from
> > __ufshcd_uic_hibern8_enter() if recovery succeeds as link is still not 
> > in hibern8,
> > upon receiving the error ufshcd_hibern8_enter() would initiate retry 
> > to put the
> > link state back into hibern8.
> >
> > Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 19 ++++++++++++++-----
> >  1 file changed, 14 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c 
> > index
> > 7a5a904..934c27a 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -3891,15 +3891,24 @@ static int __ufshcd_uic_hibern8_enter(struct
> > ufs_hba *hba)
> >                              ktime_to_us(ktime_sub(ktime_get(), 
> > start)), ret);
> >
> >         if (ret) {
> > +               int err;
> > +
> >                 dev_err(hba->dev, "%s: hibern8 enter failed. ret = 
> > %d\n",
> >                         __func__, ret);
> >
> >                 /*
> > -                * If link recovery fails then return error so that 
> > caller
> > -                * don't retry the hibern8 enter again.
> > +                * If link recovery fails then return error code 
> > (-ENOLINK)
> > +                * returned ufshcd_link_recovery().
> > +                * If link recovery succeeds then return -EAGAIN to 
> > attempt
> > +                * hibern8 enter retry again.
> You no longer returning -ENOLINK, and either way retrying, regardless
> of the error code.
> Better check that the commit log is still telling the correct story,
> taking into consideration all those recent fixes and all.

Thanks for pointing this.

Best Regards,
Can Guo.

> >                  */
> > -               if (ufshcd_link_recovery(hba))
> > -                       ret = -ENOLINK;
> > +               err = ufshcd_link_recovery(hba);
> > +               if (err) {
> > +                       dev_err(hba->dev, "%s: link recovery failed", 
> > __func__);
> > +                       ret = err;
> > +               } else {
> > +                       ret = -EAGAIN;
> > +               }
> >         } else
> >                 ufshcd_vops_hibern8_notify(hba, 
> > UIC_CMD_DME_HIBER_ENTER,
> >                                                                 
> > POST_CHANGE); @@ -3913,7 +3922,7 @@
> > static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
> >
> >         for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0; 
> > retries--) {
> >                 ret = __ufshcd_uic_hibern8_enter(hba);
> > -               if (!ret || ret == -ENOLINK)
> > +               if (!ret)
> >                         goto out;
> >         }
> >  out:
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
> > Forum,
> > a Linux Foundation Collaborative Project