Re: [PATCH 7/7] hw/watchdog/wdt_aspeed: Reduce timer precision to micro-second

[Philippe Mathieu-Daudé]

Hi Andrew,

On 6/17/20 3:18 AM, Andrew Jeffery wrote:
> On Tue, 16 Jun 2020, at 17:21, Philippe Mathieu-Daudé wrote:
>> The current implementation uses nano-second precision, while
>> the watchdog can not be more precise than a micro-second.
> 
> What's the basis for this assertion? It's true for the AST2500 and AST2600, 
> but 
> the AST2400 can run the watchdog from either a 1MHz clock source or the APB 
> clock (which must be at least 16.5MHz on palmetto). The reset state on the
> AST2400 configures the watchdog for the APB clock rate.
> 
> The Linux driver will eventually configure the watchdog for 1MHz mode
> regardless so perhaps the AST2400 reset state is a bit of a corner case, but
> I feel the assertion should be watered down a bit?

What about this description?

"The current implementation uses nano-second precision, but
 is not more precise than micro-second precision.
 Simplify by using a micro-second based timer.
 Rename the timer 'timer_us' to have the unit explicit."

> 
> Andrew
>