Re: [PATCH v1] ARM: dts: imx6sl-evk: keep sw4 always on

[Shawn Guo]

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:

 - Add required regulator-always-on for regulator nodes in DTS.
 - 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.
 - Wait for a couple of release cycles for users to migrate.
 - Add regulator driver patch back and break users who keep ignoring
   the warning.

Shawn