Hi, Subhash.
> Thanks Kim for the response.
>
> On 2016-10-06 03:28, Kiwoong Kim wrote:
> > Hi, Subhash.
> >
> > Some UFS host controllers may need to call the vendor specific
> > callback before and after controlling by clock control framework,
> > regardless of whether available clocks are turned on or off.
>
> Are you suggesting to call ufshcd_vops_setup_clocks() 2 times, one before
> the on/off by ufshcd core driver and one after the on/off? If yes, then we
> also have add 3rd argument clarifying if this is PRE_CHANGE or
POST_CHANGE.
>
> >
> > Is there any special reason to limit to invoke the callback
> > only when the clocks are turned on or not?
> >
> > Besides, the callback is acknowledged from core driver
> > because 2nd argument is whether the clocks are turned on or not.
> >
> > If you have any other idea, please let me know.
>
> This is my suggestion:
> 1. Add 3rd argument to setup_clocks ops to let the vendor callback
> function know if this is called PRE_CHANGE or POST_CHANGE.
> 2. If #1 is in place, call setup_clocks 2 times, one with PRE_CHANGE
> argument before making any clock changes in core driver, 2nd with
> POST_CHANGE argument after making the clock changes to core driver.
Yes, that's exactly the same what I mean.
Thanks
>
> Let me know if this would work or not.
>
> Thanks,
> Subhash
>
> >
> > Thanks
> > Regards
> >
> >> Vendor specific setup_clocks callback may require the clocks managed
> >> by ufshcd driver to be ON. So if the vendor specific setup_clocks
> >> callback
> >> is called while the required clocks are turned off, it could result
> >> into
> >> unclocked register access.
> >>
> >> To prevent possible unclock register access, this change makes sure
> >> that
> >> required clocks remain enabled before calling into vendor specific
> >> setup_clocks callback.
> >>
> >> Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> >> ---
> >> Changes from v2:
> >> * Don't call ufshcd_vops_setup_clocks() again for clock off
> >> ---
> >> drivers/scsi/ufs/ufshcd.c | 22 +++++++++++++++++++++-
> >> 1 file changed, 21 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> >> index 05c7456..c1a77d3 100644
> >> --- a/drivers/scsi/ufs/ufshcd.c
> >> +++ b/drivers/scsi/ufs/ufshcd.c
> >> @@ -5389,6 +5389,17 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> >> *hba, bool on,
> >> if (!head || list_empty(head))
> >> goto out;
> >>
> >> + /*
> >> + * vendor specific setup_clocks ops may depend on clocks managed by
> >> + * this standard driver hence call the vendor specific setup_clocks
> >> + * before disabling the clocks managed here.
> >> + */
> >> + if (!on) {
> >> + ret = ufshcd_vops_setup_clocks(hba, on);
> >> + if (ret)
> >> + return ret;
> >> + }
> >> +
> >> list_for_each_entry(clki, head, list) {
> >> if (!IS_ERR_OR_NULL(clki->clk)) {
> >> if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
> >> @@ -5410,7 +5421,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> >> *hba, bool on,
> >> }
> >> }
> >>
> >> - ret = ufshcd_vops_setup_clocks(hba, on);
> >> + /*
> >> + * vendor specific setup_clocks ops may depend on clocks managed by
> >> + * this standard driver hence call the vendor specific setup_clocks
> >> + * after enabling the clocks managed here.
> >> + */
> >> + if (on) {
> >> + ret = ufshcd_vops_setup_clocks(hba, on);
> >> + if (ret)
> >> + return ret;
> >> + }
> >> out:
> >> if (ret) {
> >> list_for_each_entry(clki, head, list) {
> >> --
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> >> Forum,
> >> a Linux Foundation Collaborative Project
> >>
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