Re: [PATCH v1 1/2] scsi: dt-bindings: ufs: Add vcc-voltage-level for UFS

[nguyenb]

On 2020-09-14 21:41, Bjorn Andersson wrote:
> On Tue 01 Sep 01:00 CDT 2020, Bao D. Nguyen wrote:
>
> > UFS's specifications supports a range of Vcc operating
> > voltage levels. Add documentation for the UFS's Vcc voltage
> > levels setting.
> >
> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> > Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
> > Signed-off-by: Bao D. Nguyen <nguyenb@xxxxxxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt 
> > b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> > index 415ccdd..7257b32 100644
> > --- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> > +++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> > @@ -23,6 +23,8 @@ Optional properties:
> >                            with "phys" attribute, provides phandle to 
> > UFS PHY node
> >  - vdd-hba-supply        : phandle to UFS host controller supply 
> > regulator node
> >  - vcc-supply            : phandle to VCC supply regulator node
> > +- vcc-voltage-level     : specifies voltage levels for VCC supply.
> > +                          Should be specified in pairs (min, max), 
> > units uV.
>
> What exactly are these pairs representing?
The pair is the min and max Vcc voltage request to the PMIC chip.
As a result, the regulator output voltage would only be in this range.

> Is this supposed to be 3 pairs of (min,max) for vcc, vcc and vccq2 to 
> be
> passed into a regulator_set_voltage() for each regulator?
Yes, that's right. I should include the other power supplies in this 
change as well.
> Or are these some sort of "operating points" for the vcc-supply?
>
> Regards,
> Bjorn
>
> >  - vccq-supply           : phandle to VCCQ supply regulator node
> >  - vccq2-supply          : phandle to VCCQ2 supply regulator node
> >  - vcc-supply-1p8        : For embedded UFS devices, valid VCC range 
> > is 1.7-1.95V
> > --
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> > Forum,
> > a Linux Foundation Collaborative Project