RE: [PATCH v5 7/7] scsi: ufs: Fix error handing during hibern8 enter

[Avri Altman]

> 
> 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() and if failure is encountered, link recovery
> shall put the link back to the 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>
Reviewed-by: Avri Altman <avri.altman@xxxxxxx>