linux-kernel - Re: [PATCH 1/1] rtc: pcf85063: add integrity check

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Message-ID: <SN6PR01MB4269E7C0A5B2069F96384A6BF3499@SN6PR01MB4269.prod.exchangelabs.com>
Date:   Mon, 19 Apr 2021 20:26:42 +0000
From:   "Gervais, Francois" <FGervais@...tech-controls.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Michael McCormick <michael.mccormick@...tel.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] rtc: pcf85063: add integrity check

> I'm not sure I get the use case because PCF85063_REG_CTRL2 should be
> initialized properly after the driver is probed anyway. The other two
> can be set from userspace once it detects the oscillator failure which
> would be better at deciding the policy anyway.

Thank you for the feedback I think I understand now.

We saw the reported problem on devices running kernel v5.4 which doesn't
have the common clock framework support and so PCF85063_REG_CTRL2
clkout was not initialized by the kernel and left at hardware default.

I guess with CCF support, if PCF85063_REG_CTRL2 gets corrupted on
power application, on driver probe the clkout value will be set to 0b000
or some known default.

I'm not familiar the CCF, do you know if it's the case that default values
will be set on boot?