RE: [PATCH v2] scsi: ufs: disable auto hibern8 while entering suspend

[서호영 <hy50.seo@samsung.com>]

Hi,
I think content is lacking in the UFSHCI spec.
In the process, AH8 is in operation, and it seems that sending the command
hibern8 by manual has a defeat.
I don't know what the all hci vendor's hardware design will be, but there is a possibility that ah8 and manual hibern8 may overlap.
So if is operating in ah8, it is thought that it will be safer to disable ah8 before sending hibern8 command.

> -----Original Message-----
> From: Stanley Chu [mailto:stanley.chu@mediatek.com]
> Sent: Wednesday, January 26, 2022 10:22 AM
> To: SEO HOYOUNG; linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org;
> alim.akhtar@samsung.com; avri.altman@wdc.com; jejb@linux.ibm.com;
> martin.petersen@oracle.com; beanhuo@micron.com; asutoshd@codeaurora.org;
> cang@codeaurora.org; bvanassche@acm.org; bhoon95.kim@samsung.com;
> kwmad.kim@samsung.com
> Cc: kernel test robot; peter.wang@mediatek.com
> Subject: Re: [PATCH v2] scsi: ufs: disable auto hibern8 while entering
> suspend
> 
> Hi Hoyoung,
> 
> On Tue, 2022-01-25 at 03:06 +0900, SEO HOYOUNG wrote:
> > v1-> v2: fixed no previous prototype warning
> > Reported-by: kernel test robot <lkp@intel.com>
> >
> > All warnings (new ones prefixed by >>):
> > > > drivers/scsi/ufs/ufshcd.c:4207:6: warning: no previous prototype
> >
> > for 'ufshcd_auto_hibern8_disable' [-Wmissing-prototypes]
> > 4207 | void ufshcd_auto_hibern8_disable(struct ufs_hba *hba)
> >
> > If using auto hibern8 mode, need to disable auto hibern8 while
> > entering suspend.
> > When using auto hibern8 mode, it does not seem right to send a uic
> > command
> 
> The UFSHCI spec does not mention the above rule.
> Why would you need to disable AH8 before using UIC command to enter H8?
> 
> > for entry into hibern8 in the next
> > line(ufshcd_lik_state_transition(..))
> > It seem right to send after disable auto hibern8.
> >
> > In addition, if the auto hibern8 mode supported, it is enabled in
> > resume.
> > So it seems that it will be paired only when auto hibern8 is disabled
> > while entering suspend.
> >
> > Signed-off-by: SEO HOYOUNG <hy50.seo@samsung.com>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 460d2b440d2e..a6edbbd8ca2c 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -254,6 +254,7 @@ static void
> > ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
> > static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool
> > enable);  static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
> > static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
> > +static void ufshcd_auto_hibern8_disable(struct ufs_hba *hba);
> >
> >  static inline void ufshcd_enable_irq(struct ufs_hba *hba)  { @@
> > -4204,6 +4205,18 @@ void ufshcd_auto_hibern8_update(struct ufs_hba
> > *hba, u32 ahit)  }  EXPORT_SYMBOL_GPL(ufshcd_auto_hibern8_update);
> >
> > +static void ufshcd_auto_hibern8_disable(struct ufs_hba *hba) {
> > +	unsigned long flags;
> > +
> > +	if (!ufshcd_is_auto_hibern8_supported(hba))
> > +		return;
> > +
> > +	spin_lock_irqsave(hba->host->host_lock, flags);
> > +	ufshcd_writel(hba, 0, REG_AUTO_HIBERNATE_IDLE_TIMER);
> > +	spin_unlock_irqrestore(hba->host->host_lock, flags); }
> > +
> >  void ufshcd_auto_hibern8_enable(struct ufs_hba *hba)  {
> >  	unsigned long flags;
> > @@ -8925,6 +8938,7 @@ static int __ufshcd_wl_suspend(struct ufs_hba
> > *hba, enum ufs_pm_op pm_op)
> >  	 * with the link off, so do not check for bkops.
> >  	 */
> >  	check_for_bkops = !ufshcd_is_ufs_dev_deepsleep(hba);
> > +	ufshcd_auto_hibern8_disable(hba);
> >  	ret = ufshcd_link_state_transition(hba, req_link_state,
> > check_for_bkops);
> >  	if (ret)
> >  		goto set_dev_active;