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

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Message-ID: <CAJ+vNU0voeMW06Je6nyrV1Ud3sT8Us+RACcQtsKUwKVaXF+dQw@mail.gmail.com>
Date:   Thu, 8 Sep 2022 12:25:46 -0700
From:   Tim Harvey <tharvey@...eworks.com>
To:     Marek Vasut <marex@...x.de>, Stephen Boyd <sboyd@...nel.org>
Cc:     Matti Vaittinen <mazziesaccount@...il.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>,
        NXP Linux Team <linux-imx@....com>,
        Michael Turquette <mturquette@...libre.com>
Subject: Re: BD71847 clk driver disables clk-32k-out causing RTC/WDT failure

On Thu, Sep 8, 2022 at 9:55 AM Marek Vasut <marex@...x.de> wrote:
>
> On 9/8/22 18:00, Tim Harvey wrote:
> > On Thu, Sep 1, 2022 at 9:14 PM Matti Vaittinen <mazziesaccount@...il.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?
>
> No. You can read the discussion above.

Marek,

I wasn't on the linux-clk list at that time so can't respond to the
thread but the discussion seems to have died out a couple of months
ago with no agreement between you or Stephen on how to deal with it.

So where do we take this from here? It looks like there are about 18
boards with dt's using "rohm,bd718*" which would all have non working
RTC/WDOG with CONFIG_COMMON_CLK_BD718XX enabled (which it is in
arch/arm64/configs/defconfig) right?

$ git grep "rohm,bd718" arch/ | cut
-d: -f1
arch/arm64/boot/dts/freescale/imx8mm-beacon-som.dtsi
arch/arm64/boot/dts/freescale/imx8mm-data-modul-edm-sbc.dts
arch/arm64/boot/dts/freescale/imx8mm-emcon.dtsi
arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi
arch/arm64/boot/dts/freescale/imx8mm-var-som.dtsi
arch/arm64/boot/dts/freescale/imx8mm-venice-gw7901.dts
arch/arm64/boot/dts/freescale/imx8mm-venice-gw7902.dts
arch/arm64/boot/dts/freescale/imx8mm-venice-gw7903.dts
arch/arm64/boot/dts/freescale/imx8mm-venice-gw7904.dts
arch/arm64/boot/dts/freescale/imx8mn-beacon-som.dtsi
arch/arm64/boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi
arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
arch/arm64/boot/dts/freescale/imx8mn-var-som.dtsi
arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts
arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts
arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
arch/arm64/boot/dts/freescale/imx8mq-pico-pi.dts

Best Regards,

Tim