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
