linux-kernel - Re: BD71847 clk driver disables clk-32k-out causing RTC/WDT failure

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Message-ID: <59b6dd0a-7cbb-5dbd-8da0-57baeba3327e@gmail.com>
Date:   Fri, 2 Sep 2022 07:14:01 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     Tim Harvey <tharvey@...eworks.com>,
        linux-clk <linux-clk@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Fabio Estevam <festevam@...il.com>,
        Shawn Guo <shawnguo@...nel.org>
Cc:     NXP Linux Team <linux-imx@....com>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Marek Vasut <marex@...x.de>
Subject: Re: BD71847 clk driver disables clk-32k-out causing RTC/WDT failure

Hi Tim,

On 9/2/22 01:23, Tim Harvey wrote:
> Greetings,
> 
> I've found that the bd71847 clk driver (CONFIG_COMMON_CLK_BD718XX
> drivers/clk/clk-bd718x7.c) disables clk-32k-out (the BD71847 C32K_OUT
> pin) which is connected IMX8MM RTC_XTALI which ends up disabling the
> IMX RTC as well as the IMX WDOG functionality.

//snip

> This happens via clk_unprepare_unused() as nothing is flagging the
> clk-32k-out as being used. What should be added to the device-tree to
> signify that this clk is indeed necessary and should not be disabled?

I have seen following proposal from Marek Vasut:

https://lore.kernel.org/all/20220517235919.200375-1-marex@denx.de/T/#m52d6d0831bf43d5f293e35cb27f3021f278d0564

I am not sure if the discussion is completed though. I guess it was 
agreed this was needed/usefull and maybe the remaining thing to decide 
was just the property naming.

Best Regards
	-- Matti

-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~