[U-Boot] [PATCH] CFI Driver: Reset watchdog timer after each flash operation

[Graeme Russ]

On Sun, Oct 4, 2009 at 10:15 PM, Ingo van Lil <inguin at gmx.de> wrote:
> On 10/04/2009 01:29 AM, Wolfgang Denk wrote:
>
>> No, not an exception, but the reference implementation. I cannot help
>> it that most other architectures / SoCs don;t care much.
>
> Well, if such an uncommon side-effect is expected of a function with a
> well-known name it should at least be prominently documented. I like
> Mike's suggestion to have a central udelay() implementation for that;
> I'm gonna try to whip up a patch tomorrow.
>
>
>>> I'm using an Atmel AT91-based custom board, and the udelay() function
>>> can be found in cpu/arm926ejs/at91/timer.c. Unfortunately there's no
>>> central udelay() implementation in lib_arm.
>>
>> Guess nobody attempted to use a WD on such a system before.
>
> You hardly have a choice: After reset the AT91's watchdog timer runs at
> maximum period (15 seconds), and the control register is one-time
> writable. If you disable the watchdog in u-boot there's no way to
> re-enable it later in the OS.
>
> Regards,
> Ingo

Naive question of the day - Is there any reason for the complexity of the
watchdog implementation with all the #defines to sort out software and
hardware resets?

Wouldn't it be easier to replace it with a weak function with an empty
default implementation over-ridden at the board/arch/cpu level as needed?

We can then call the watchdog reset in udelay() - will be a problem if the
watchdog needs udelay (for a timed reset pulse for example)

Just a thought

Regards,

Graeme