Am Freitag, 29. August 2014, 21:51:46 schrieb Doug Anderson: > Santosh, > > On Thu, Aug 28, 2014 at 2:26 PM, Santosh Shilimkar > > <santosh.shilimkar@xxxxxx> wrote: > > On Thursday 28 August 2014 03:36 PM, Doug Anderson wrote: > >> These two patches add support for automatically configuring the IO > >> voltage domains on rk3188 and rk3288 SoCs. The first patch adds some > >> new notification types to the regulator code. It's used by the second > >> patch which actually implements the IO voltage domain driver. > >> > >> These two patches were co-developed by Heiko Stübner and Doug Anderson > >> (proof of concept patches were written by Heiko). They were tested in > >> a private branch on an rk3288 board using rk808 instead of mainline > >> since rk808 support isn't finalized in mainline yet. > >> > >> (sorry if you got this series twice; my mailer seems unhappy with me) > >> > >> Heiko Stübner (2): > >> regulator: core: Add REGULATOR_EVENT_PRE_VOLTAGE_CHANGE (and ABORT) > >> soc/rockchip: io-domain: add driver handling io domains > > > > Sorry to shot down but your IO domains are nothing but voltage domains > > and you should really build something in the drivers/power/* > > If everyone agrees that this belongs in drivers/power that's totally > OK. Neither Heiko nor I was confident that it should be in > drivers/soc. I had even though that the code wouldn't be totally out > of place in the Rockchip pinctrl driver (adding Linus W since I think > some SoCs did add code to handle 3.3V vs. 1.8V in pinctrl). a bit of context for Linus ... This is essentially the continuation of the thread "io-domain voltages as regulators?" from the beginning of august. After more discussions we found out that the io voltage selection I asked about is not an independent supply, but instead has to reflect the voltage of the real supplying regulator. And setting the io-voltage setting to 1.8V while the regulator is supplying 3.3V for example may actually damage the chip. So in our current approach here, we added a driver that tracks voltage changes of the supplying regulator via a notifier and sets the register bits accordingly. > > > Please have a look at the RFC [1]. You should really go on those > > lines and collaborate to make a generic voltage domain layer instead of > > throwing the driver under drivers/soc. > > Trying to base things on a 7-month old RFC that hasn't been touched is > not something I'm going to do. Maybe that makes me a bad person... > > I would also say that I'm not convinced that we really need a > complicated framework here. Maybe when we're talking about things > like ABB and DevFreq and the like then having a nice framework is a > good idea. Really here we're just setting properties associated with > IO pins. There's no decisions about latency, power tradeoffs, etc. > If the pin is connected to 1.8V we need to set the 1.8V bit. If it's > connected to 3.3V we need to set the 3.3V bit. The end. > > The only remotely complicated thing (and why this isn't just a pinctrl > property) is what happens with dynamic voltages. SD Card IO lines can > change voltage depending on UHS negotiation. In that case the SD Card > Driver will request that its regulator change from 3.3V to 1.8V. The > bit in the IO domain register needs to update in tandem. > > > The driver is really quite tiny (333 lines). If we find that lots of > people copy it and they have code that's nearly the same then we > should try to abstract things out then. > > > I'd be interested in hearing other opinions, though. > > -Doug -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
