[Letux-kernel] Palmas wtchdog driver?

H. Nikolaus Schaller hns at goldelico.com
Sat Dec 15 08:50:12 CET 2018


Hi Tony,

> Am 13.12.2018 um 19:14 schrieb Tony Lindgren <tony at atomide.com>:
> 
> * H. Nikolaus Schaller <hns at goldelico.com> [181208 21:35]:
>> Hi Tony,
>> I had the OMAP5 running very very hot by a kernel hang (most likely a spinlock).
>> And I wondered if there is no safety mechanism (watchdog timer).
>> 
>> I did a little research and there seems to be no WDT driver for the Palmas in
>> mainline.
>> 
>> There was something:
>> 
>> 	https://lore.kernel.org/patchwork/patch/367777/
>> 
>> but it seems it did not arrive upstream.
>> Any reasons or problems with the driver? Or a newer version sitting in some
>> git?
> 
> Sorry no idea. Maybe check if it's similar to the
> drivers/watchdog/twl4030_wdt.c?

Yes, it is. Code structure is almost the same, because it is based on twl4030 code :)

Differences:
* uses enable/disable instead of start/stop (probably older WDT core API and easy to fix)
* different compatible list (obviously necessary)
* uses palmas_write() from include/linux/mfd/palmas.h instead of twl_i2c_write_u8() from include/linux/mfd/twl.h
* (have not checked): probably different register offsets
* has no remove/suspend/resume handlers (probably older WDT core API and easy to copy&paste)

But there seems to be a bug in palmas_wdt_write(). IMHO it ignores the "data"
argument when passing down to palmas_write()...

So it may be that the driver did not work as proposed.

I am not sure but I think I had spotted a v10 of the patch set.

Ah, yes:

	https://lore.kernel.org/patchwork/patch/367819/

There are already several review comments (including confirmation of
the data argument issue) but I could not find a v11 or v12.

> 
> Note that some devices just use drivers/watchdog/omap_wdt.c
> that is wired to the PMIC used. So maybe the Palmas WDT
> was just forgotten if it was not needed?

Maybe it was simply forgotten to be completed and resubmitted.

I am not sure if Graeme is still actively working on this
topic. So I put him on CC.

BR and thanks,
Nikolaus




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