linux-kernel - Re: [PATCH 4/4] ARM64: dts: imx: add i.MX8QXP system controller RTC support

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Message-ID: <20181128095823.GE8952@piout.net>
Date:   Wed, 28 Nov 2018 10:58:23 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Anson Huang <anson.huang@....com>
Cc:     Lothar Wa��mann <LW@...O-electronics.de>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        Aisheng DONG <aisheng.dong@....com>,
        Andy Gross <andy.gross@...aro.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "horms+renesas@...ge.net.au" <horms+renesas@...ge.net.au>,
        "heiko@...ech.de" <heiko@...ech.de>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "enric.balletbo@...labora.com" <enric.balletbo@...labora.com>,
        "amit.kucheria@...aro.org" <amit.kucheria@...aro.org>,
        "ezequiel@...labora.com" <ezequiel@...labora.com>,
        "olof@...om.net" <olof@...om.net>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 4/4] ARM64: dts: imx: add i.MX8QXP system controller RTC
 support

On 28/11/2018 09:41:22+0000, Anson Huang wrote:
> > > i.MX SoCs ONLY have 1 RTC. And RTC are always enabled by default for
> > > all i.MX SoCs, so do we have to disable it here and enable it in board dts?
> > >
> > 
> > I would say that most of the i.MX based boards include another RTC because
> > the SoC one consumes way too much power.
> > 
> > Note that I don't care too much whether it is enabled by default, I was simply
> > explaining why you may want to disable it by default.
> 
> OK, this system controller RTC is a little different, it is controlled by system controller firmware,
> and system controller firmware will always select the best one for its user(Linux kernel) if there are other
> RTCs available, so I think we can keep it enabled by default for now. Thanks.
> 

Do you mean that the plan is to push support for the external RTCs (e.g.
the i2c ones) to the M4 firmware?

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com