Re: [Linaro-acpi] [PATCH v8 5/5] Watchdog: introduce ARM SBSA watchdog driver

[Timur Tabi]

Fu Wei wrote:
> SBSA 2.3 Page 23 :
> Note: the watchdog offset register is 32 bits wide. This gives a
> maximum watch period of around 10s at a system
> counter frequency of 400MHz. If a larger watch period is required then
> the compare value can be programmed
> directly into the compare value register.
>
> 214s means your system counter is approximately at 20MHz which is in
> the range of (10MHz ~ 400MHz)
>
> SBSA 2.3 Page 13 :
> The System Counter (of the Generic Timer) shall run at a minimum
> frequency of 10MHz and maximum of
> 400MHz.

Thanks, that explains a lot.

If we expected customers to have a lower system counter frequency, then 
we wouldn't have to worry about the timeouts being too short.  It seems 
to me that the SBSA spec says that if you want a longer timeout, you 
have to lower the frequency.  We shouldn't be complicating the driver 
because some customers might not follow the spec.

--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
Code Aurora Forum, hosted by The Linux Foundation.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/