Re: [PATCH v2 2/2] scsi: ufs: core: Replace hard coded vcc-off delay with a variable

[Bao D. Nguyen]

On 10/12/2025 8:58 PM, Peter Wang (王信友) wrote:
> On Thu, 2025-10-09 at 13:10 -0700, Bao D. Nguyen wrote:
> > +       /*
> > +        * Most ufs devices require 1ms delay after vcc is powered
> > off before
> > +        * it can be powered on again. Set the default to 5ms. The
> > platform
> > +        * drivers can override this setting as needed.
> > +        */
> > +       hba->sleep_post_vcc_off = 5000;
> > +
>
> Hi Bao,
>
> Since 2ms is sufficient for most devices, wouldn't it make
> sense to set the default value to 2ms?

Agree Peter. This was my preference as well.

> >          init_completion(&hba->dev_cmd.complete);
> >
> >          err = ufshcd_hba_init(hba);
> > diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> > index 1d39437..ad49979 100644
> > --- a/include/ufs/ufshcd.h
> > +++ b/include/ufs/ufshcd.h
> > @@ -1140,6 +1140,8 @@ struct ufs_hba {
> >          int critical_health_count;
> >          atomic_t dev_lvl_exception_count;
> >          u64 dev_lvl_exception_id;
> > +
> > +       u32 sleep_post_vcc_off;
>
> The name sleep_post_vcc_off might be misunderstood as a
> status or a flag. I suggest changing it to a more explicit
> name, such as vcc_off_delay_ms.

Sure Peter. I will make the change.

Thanks, Bao

> Thanks
> Peter