[PATCH 2/8] watchdog: s3c2410: Fix infinite interrupt in soft mode

[krzk@kernel.org (Krzysztof Kozlowski)]

On Fri, Feb 24, 2017 at 07:37:53AM -0800, Guenter Roeck wrote:
> On 02/24/2017 07:11 AM, Krzysztof Kozlowski wrote:
> > In soft (no-reboot) mode, the driver self-pings watchdog upon expiration
> > of an interrupt.  However the interrupt itself was not cleared thus on
> > first hit, the system enters infinite interrupt handling loop.
> > 
> > On Odroid U3 (Exynos4412), when booted with s3c2410_wdt.soft_noboot=1
> > argument the console is flooded:
> > 	# killall -9 watchdog
> > 	[   60.523760] s3c2410-wdt 10060000.watchdog: watchdog timer expired (irq)
> > 	[   60.536744] s3c2410-wdt 10060000.watchdog: watchdog timer expired (irq)
> > 
> > Fix this by writing something to the WTCLRINT register to clear the
> > interrupt.  The register WTCLRINT however appeared in S3C6410 so a new
> > watchdog quirk and flavor are needed.
> > 
> > Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> 
> > 
> > ---
> > 
> > I was thinking about CC-ing stable, especially when I thought about
> > adding unconditional WTCLRINT clear.  However it appears that S3C2410
> > does not have the WTCLRINT register, this a new chip flavor has to be
> > added.  This makes the fix spread over driver and DTS changes.
> > 
> > Worth adding:
> > 	Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > ?
> 
> How would that be different to Cc: stable ?

I guess not much... except for the metrics that some bug was fixed.

Best regards,
Krzysztof