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

nguyenb
2020-09-15T08:25:08Z

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@codeaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
>> Signed-off-by: Bao D. Nguyen <nguyenb@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.

>
> 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
>>