Re: [PATCH] scsi: ufs: Don't disable core_clk_unipro if the link is active

[Can Guo <cang@xxxxxxxxxxxxxx>]

Hi Stanley,

On 2020-11-24 13:20, Stanley Chu wrote:
> Hi Can,
>
> On Mon, 2020-11-23 at 21:05 -0800, Can Guo wrote:
> > If we want to disable clocks but still keep the link active, both 
> > ref_clk
> > and core_clk_unipro should be skipped.
>
> "core_clk_unipro" seems used by ufs-qcom only and not defined in the 
> UFS
> platform binding document: ufshcd_pltfrm.txt.

Agree.

> Could you please add the definition first and then it would be
> reasonable to be used in common driver?
>
> Or, how about add a flag in struct ufs_clk_info indicating if this 
> clock
> needs be ON to keep the link active? The flag could be set properly by
> vendor initialization functions. In this way, we can also remove the
> hard-coded "ref_clk" in __ufshcd_setup_clocks().

This seems better, I will upload next version to incorporate the idea
after it is tested.

Thanks,

Can Guo.

> Thanks.
> Stanley Chu
>
> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index a7857f6..69c2e91 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -222,7 +222,7 @@ static int ufshcd_clear_tm_cmd(struct ufs_hba 
> > *hba, int tag);
> >  static void ufshcd_hba_exit(struct ufs_hba *hba);
> >  static int ufshcd_probe_hba(struct ufs_hba *hba, bool async);
> >  static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
> > -				 bool skip_ref_clk);
> > +				 bool keep_link_active);
> >  static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on);
> >  static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba);
> >  static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba 
> > *hba);
> > @@ -1710,7 +1710,6 @@ static void ufshcd_gate_work(struct work_struct 
> > *work)
> >  	if (!ufshcd_is_link_active(hba))
> >  		ufshcd_setup_clocks(hba, false);
> >  	else
> > -		/* If link is active, device ref_clk can't be switched off */
> >  		__ufshcd_setup_clocks(hba, false, true);
> >
> >  	/*
> > @@ -7991,7 +7990,7 @@ static int ufshcd_init_hba_vreg(struct ufs_hba 
> > *hba)
> >  }
> >
> >  static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
> > -					bool skip_ref_clk)
> > +					bool keep_link_active)
> >  {
> >  	int ret = 0;
> >  	struct ufs_clk_info *clki;
> > @@ -8009,7 +8008,13 @@ static int __ufshcd_setup_clocks(struct ufs_hba 
> > *hba, bool on,
> >
> >  	list_for_each_entry(clki, head, list) {
> >  		if (!IS_ERR_OR_NULL(clki->clk)) {
> > -			if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
> > +			/*
> > +			 * To keep link active, ref_clk and core_clk_unipro
> > +			 * should be kept ON.
> > +			 */
> > +			if (keep_link_active &&
> > +			    (!strcmp(clki->name, "ref_clk") ||
> > +			     !strcmp(clki->name, "core_clk_unipro")))
> >  				continue;
> >
> >  			clk_state_changed = on ^ clki->enabled;
> > @@ -8580,7 +8585,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, 
> > enum ufs_pm_op pm_op)
> >  	if (!ufshcd_is_link_active(hba))
> >  		ufshcd_setup_clocks(hba, false);
> >  	else
> > -		/* If link is active, device ref_clk can't be switched off */
> >  		__ufshcd_setup_clocks(hba, false, true);
> >
> >  	if (ufshcd_is_clkgating_allowed(hba)) {