Hi, Shawn Anson Huang Best Regards!
> -----Original Message----- > From: Shawn Guo [mailto:shawn...@kernel.org] > Sent: Tuesday, July 3, 2018 1:39 PM > To: Robin Gong <yibin.g...@nxp.com> > Cc: feste...@gmail.com; Anson Huang <anson.hu...@nxp.com>; > mark.rutl...@arm.com; devicet...@vger.kernel.org; > linux-kernel@vger.kernel.org; robh...@kernel.org; dl-linux-imx > <linux-...@nxp.com>; ker...@pengutronix.de; Fabio Estevam > <fabio.este...@nxp.com>; linux-arm-ker...@lists.infradead.org > Subject: Re: [PATCH v1] ARM: dts: imx6sl-evk: keep sw4 always on > > On Mon, Jul 02, 2018 at 02:12:52AM +0000, Robin Gong wrote: > > But in fact, the original dts is not correct without > > 'regulator-always- on'since SW4 is the critical DDR power rail, > > although, it's kept on in the previous kernel by no switches > > enable/disable interfaces provided in pfuze driver. Adding new > > property which can be done totally by the common 'regulator-always-on' > > is not a good choice. Keep the dts patch adding 'regulator-always-on' > > ahead of pfuze driver pach adding enable/disable interface is enough for > > such > case I think. > > We can not just break the installed DTBs like this. If patching regulator > driver > with a new property is really difficult, we could migrate the existing users > in a > 'soft' way: Patching regulator driver needs to add property for those regulators can be OFF, it will make users confuse with original regulator framework knowledge, NOT a good idea. > > - Add required regulator-always-on for regulator nodes in DTS. I & Yibin already sent out patch to add " regulator-always-on " for regulator nodes in DTS, so they can be applied first? > - Patch i.MX platform code to check the presence of regulator-always-on > property for critical regulators, and give a big warning if it's > missing. It is NOT easy to identify which switch is critical or NOT, and different platforms have different board design, it will introduce many platform specified code, so I think just revert the pfuze100 switch enable/disable patch should be OK for now. > - Wait for a couple of release cycles for users to migrate. > - Add regulator driver patch back and break users who keep ignoring > the warning. After a couple of release cycles, add the pfuze100 switch enable/disable patch back to support this feature, I believe users should switch to new dtb with "regulator-always-on" existing already. Anson. > > Shawn
