Re: [PATCH V1 0/3] scsi: ufs: Add a vops to configure VCC voltage level

[nitirawa]

On 2021-02-01 14:01, nitirawa@xxxxxxxxxxxxxx wrote:
> On 2021-01-31 19:32, Avri Altman wrote:
> > > UFS specification allows different VCC configurations for UFS 
> > > devices,
> > > for example,
> > >         (1)2.70V - 3.60V (For UFS 2.x devices)
> > >         (2)2.40V - 2.70V (For UFS 3.x devices)
> > > For platforms supporting both ufs 2.x (2.7v-3.6v) and
> > > ufs 3.x (2.4v-2.7v), the voltage requirements (VCC) is 2.4v-3.6v.
> > > So to support this, we need to start the ufs device initialization 
> > > with
> > > the common VCC voltage(2.7v) and after reading the device descriptor 
> > > we
> > > need to switch to the correct range(vcc min and vcc max) of VCC 
> > > voltage
> > > as per UFS device type since 2.7v is the marginal voltage as per 
> > > specs
> > > for both type of devices.
> > >
> > > Once VCC regulator supply has been intialised to 2.7v and UFS device
> > > type is read from device descriptor, we follows below steps to
> > > change the VCC voltage values.
> > >
> > > 1. Set the device to SLEEP state.
> > > 2. Disable the Vcc Regulator.
> > > 3. Set the vcc voltage according to the device type and reenable
> > >    the regulator.
> > > 4. Set the device mode back to ACTIVE.
> > >
> > > The above changes are done in vendor specific file by
> > > adding a vops which will be needed for platform
> > > supporting both ufs 2.x and ufs 3.x devices.
> > The flow should be generic - isn't it?
> > Why do you need the entire flow to be vendor-specific?
> > Why not just the parameters vendor-specific?
> >
> > Thanks,
> > Avri
>
> Hi Avri,
> This vops change was done as per the below mail thread
> discussion where it was decided to go with vops and
> let vendors handle it, until specs provides more clarity.
>
> https://www.spinics.net/lists/kernel/msg3754995.html
>
> Regards,
> Nitin

Hi Avri,
Please let me know if you have any further comments on this.

Regards,
Nitin