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

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Date:   Thu, 8 Sep 2022 22:39:03 +0200
From:   Marek Vasut <marex@...x.de>
To:     Tim Harvey <tharvey@...eworks.com>, 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 9/8/22 21:25, Tim Harvey wrote:
> 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?

Feel free to continue the effort.