Re: [PATCH] watchdog: via_wdt: Partial fix for programming error and support additional southbridges

[Guenter Roeck <linux@roeck-us.net>]

On 05/18/2015 03:50 AM, Nick & John wrote:
>      This patch fixes a programming error by limiting WDT_TIMEOUT_MAX to 255.
>      That is done to avoid invalid settings. Putting a value bigger than 255
>      results in non working watchdog and reset is not performed. We are trying
>      to fit a 10bit value to an 8bit area! To support 1023 seconds MMIO addr+5
>      bit1:0 must be used to store the last(higher) two bits of count number.
>      Strangely no error was logged at the system when using values bigger than
>      255, the driver just ignores the time count.
>

While I have no idea why, the watchdog in this driver is pinged using a soft timer,
and it is always pinged every 0.5 seconds. So reducing the maximum timeout is not
necessary; in fact the driver could support a higher timeout.

The real fix, if it is really necessary, would be to either store the upper bits
as suggested above, or to just program the chip to a timeout of 255 seconds
if the desired timeout is larger than 255.

>      Also it adds support for VT8235 and VT8237 series southbridges. Tested with
>      VT8235M, VT8237 and VT8237S boards.
>
This should be a separate patch; see Documentation/SubmittingPatches, chapter 3.

Thanks,
Guenter