On Tue 15 Sep 16:47 UTC 2020, nguyenb@xxxxxxxxxxxxxx wrote: > On 2020-09-15 06:43, Bjorn Andersson wrote: > > On Tue 15 Sep 03:14 CDT 2020, nguyenb@xxxxxxxxxxxxxx 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 <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. > > > > > > > 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 > Thank you all for your comments. The current driver hardcoding 2.7V Vcc min > voltage > does not work for UFS3.0+ devices according to the UFS device JEDEC spec. > However, we will > try to address it in a different way. > Right, but what I'm saying is that you should remove the regulator_set_voltage() call from the driver and rely on the device's dts, in which case you won't have this problem. Thanks, Bjorn > Regards, > Bao > > > > > > > > > > > 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 > > > > >
