On Tue 15 Sep 03:14 CDT 2020, nguy...@codeaurora.org wrote: > 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 <c...@codeaurora.org> > > > Signed-off-by: Asutosh Das <asuto...@codeaurora.org> > > > Signed-off-by: Bao D. Nguyen <nguy...@codeaurora.org> > > > --- > > > 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. >
If you have static min/max voltage constraints for a device on a particular board the right way to handle this is to adjust the board's regulator-min-microvolt and regulator-max-microvolt accordingly - and not call regulator_set_voltage() from the river at all. In other words, you shouldn't add this new property to describe something already described in the node vcc-supply points to. Regards, Bjorn > > > > 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 > > > -- > > > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora > > > Forum, > > > a Linux Foundation Collaborative Project > > >
