From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shawn Guo Subject: Re: [PATCH v1] ARM: dts: imx6sl-evk: keep sw4 always on Date: Tue, 3 Jul 2018 13:38:45 +0800 Message-ID: <20180703053843.GC4348@dragon> References: <1530526335.15665.13.camel@nxp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <1530526335.15665.13.camel@nxp.com> Sender: linux-kernel-owner@vger.kernel.org To: Robin Gong Cc: "festevam@gmail.com" , Anson Huang , "mark.rutland@arm.com" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , dl-linux-imx , "kernel@pengutronix.de" , Fabio Estevam , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org 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