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


    Anson Huang
    Best Regards!


    > -----Original Message-----
    > From: Fabio Estevam [mailto:festevam@gmail.com]
    > Sent: Monday, July 2, 2018 7:33 AM
    > To: Shawn Guo <shawnguo@kernel.org>; Anson Huang
    > <anson.huang@nxp.com>
    > Cc: Robin Gong <yibin.gong@nxp.com>; Mark Rutland
    > <mark.rutland@arm.com>; open list:OPEN FIRMWARE AND FLATTENED
    > DEVICE TREE BINDINGS <devicetree@vger.kernel.org>; linux-kernel
    > <linux-kernel@vger.kernel.org>; Rob Herring <robh+dt@kernel.org>;
    > dl-linux-imx <linux-imx@nxp.com>; Sascha Hauer <kernel@pengutronix.de>;
    > Fabio Estevam <fabio.estevam@nxp.com>; moderated list:ARM/FREESCALE
    > IMX / MXC ARM ARCHITECTURE <linux-arm-kernel@lists.infradead.org>
    > Subject: Re: [PATCH v1] ARM: dts: imx6sl-evk: keep sw4 always on
    >
    > On Sun, Jul 1, 2018 at 6:34 AM, Shawn Guo <shawnguo@kernel.org> wrote:
    > > On Mon, Jun 25, 2018 at 08:34:11PM +0800, Robin Gong wrote:
    > >> SW4 is one power rail for LPDDR2 on i.mx6sl-evk, so it should be kept
    > >> always on. But it's disabled after switch disabled interface
    > >> implemented in pfuze driver 'commit 5fe156f1cab4
    > >> ("regulator: pfuze100: add enable/disable for switch")'.Thus, it
    > >> breaks kernel bootup. Add 'regulator-always-on' for SW4.
    > >>
    > >> Signed-off-by: Robin Gong <yibin.gong@nxp.com>
    > >
    > > Does that mean boards with existing DTB installed will stop working
    > > with new kernel? That's bad, and the kernel commit should probably be
    > > reverted.
    >
    > Yes, this is a good point.
    >
    > Anson,
    >
    > Should 5fe156f1cab4 ("regulator: pfuze100: add enable/disable for
    > switch") be reverted to avoid such breakage?

    Yes, I think we can revert it to avoid breakage. Didn't notice that some
    i.MX platform do NOT have those critical switches always-on.

    Anson.

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