> > >>>> Hi Stanley > > >>>> > > >>>> Thanks for the patch. Bao (nguyenb) was also working towards > something > > >>>> similar. > > >>>> Would it be possible for you to take into account the scenario in > which the > > >>>> same platform supports both 2.x and 3.x UFS devices? > > >>>> > > >>>> These've different voltage requirements, 2.4v-3.6v. > > >>>> I'm not sure if standard dts regulator properties can support this. > > >>>> > > >>> > > >>> What is the actual voltage requirement for these devices and how > does > > >>> the software know what voltage to pick in this range? > > >>> > > >>> Regards, > > >>> Bjorn > > >>> > > >>>> -asd > > >>>> > > >>>> > > >>>> -- > > >>>> The Qualcomm Innovation Center, Inc. is a member of the Code > Aurora Forum, > > >>>> Linux Foundation Collaborative Project > > >> > > >> For platforms that support both 2.x (2.7v-3.6v) and 3.x (2.4v-2.7v), the > > >> voltage requirements (Vcc) are 2.4v-3.6v. The software initializes the > > >> ufs device at 2.95v & reads the version and if the device is 3.x, it may > > >> do the following: > > >> - Set the device power mode to SLEEP > > >> - Disable the Vcc > > >> - Enable the Vcc and set it to 2.5v > > >> - Set the device power mode to ACTIVE > > >> > > >> All of the above may be done at HS-G1 & moved to max supported gear > > >> based on the device version, perhaps? > > > > > > Hi Asutosh, > > > > > > Thanks for sharing this idea. > > > > > > 1. I did not see above flow defined in UFS specifications, please > > > correct me if I was wrong. > > > > > > 2. For above flow, the concern is that I am not sure if all devices > > > supporting VCC (2.4v - 2.7v) can accept higher voltage, say 2.95v, for > > > version detection. > > > > > > 3. For version detection, another concern is that I am not sure if all > > > 3.x devices support VCC (2.4v - 2.7v) only, or in other words, I am not > > > sure if all 2.x devices support VCC (2.7v - 3.6v) only. The above rule > > > will break any devices not obeying this "conventions". > > > > > > For platforms that support both 2.x (2.7v-3.6v) and 3.x (2.4v-2.7v), > > > > > > It would be good for UFS drivers detecting the correct voltage if the > > > protocol is well-defined in specifications. Until that day, any > > > "non-standard" way may be better implemented in vendor's ops? > > > > > > If the vop concept works on your platform, we could still keep struct > > > ufs_vreg and allow vendors to configure proper min_uV and max_uV to > make > > > regulator_set_voltage() works during VCC toggling flow. Without specific > > > vendor configurations, min_uV and max_uV would be NULL by default > and > > > UFS core driver will only enable/disasble VCC regulator only without > > > adjusting its voltage. > > > > > > > I think this would work. Do you plan to implement this? > > If not, I can take this up. Please let me know. > > Thanks for the understanding and support. > > I would like to re-post this patch to simply removing the pre-defined > initial values of all device powers. > > For vop idea supporting the voltage detection way, could you please take > it up since this would be better to fit what you need for fixing this > issue? Again - why vop and not a dts flag? The platform owner is aware of which device ships on which platform, isn't it? Thanks, Avri
