[Letux-kernel] Palmas wtchdog driver?

Graeme Gregory gg at slimlogic.co.uk
Sat Dec 15 10:01:59 CET 2018



On Sat, 15 Dec 2018, at 7:50 AM, H. Nikolaus Schaller wrote:
> 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.
> 
TImageddon ended my access to the documentation on that chip as I was contracted for it. I never saw the actual release version of the chip :-(

Graeme


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