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

From: Tim Harvey <tharvey@gateworks.com>
To: Matti Vaittinen <mazziesaccount@gmail.com>, Marek Vasut <marex@denx.de>
Cc: linux-clk <linux-clk@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	Fabio Estevam <festevam@gmail.com>,
	Shawn Guo <shawnguo@kernel.org>,
	NXP Linux Team <linux-imx@nxp.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Michael Turquette <mturquette@baylibre.com>
Subject: Re: BD71847 clk driver disables clk-32k-out causing RTC/WDT failure
Date: Thu, 8 Sep 2022 09:00:10 -0700	[thread overview]
Message-ID: <CAJ+vNU2FVQRwCa3DnOwkFjaZg-ntFLZmetwDbSggDXDdwOOGTg@mail.gmail.com> (raw)
In-Reply-To: <59b6dd0a-7cbb-5dbd-8da0-57baeba3327e@gmail.com>

On Thu, Sep 1, 2022 at 9:14 PM Matti Vaittinen <mazziesaccount@gmail.com> wrote:
>
> 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
>

Thanks Matti,

Marek - has there been any progress on determining how best to keep
certain clocks from being disabled?

Best Regards,

Tim