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

From: Marek Vasut
Date: Thu Sep 08 2022 - 12:57:11 EST


On 9/8/22 18:00, Tim Harvey wrote:
On Thu, Sep 1, 2022 at 9:14 PM Matti Vaittinen <mazziesaccount@xxxxxxxxx> 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@xxxxxxx/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.