[PATCH] watchdog: rti: drop hack manipulating WDT clock rate

[Jan Kiszka]

On 20.11.24 23:24, A. Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin at siemens.com>
> 
> The hack itself seems to be copied from Linux rti_wdt.c, but the WDT reset
> principle is different in U-Boot. While Linux relies on correct frequencies
> and timers and doesn't check the actual WDT counter value U-Boot driver
> seems to be more rubust: it does compare RTIDWDCNTR vs RTIDWDPRLD.

robust

> 
> Now the root cause of the original motivation to manipulate the clock rate
> is said to be understood and fixed in Linux commit cae58516534e
> ("watchdog: rti_wdt: Set min_hw_heartbeat_ms to accommodate a safety margin")
> which simultaneously removed the hack itself.
> 
> While is fix part of the mentioned patch is neither applicable nor requied

required

> for the U-Boot driver just drop the hack setting WDT clock rate to 90% of
> the real rate. This has a nice effect that the WDT timeout is now as
> requested and not 10% shorter.
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin at siemens.com>
> ---
>  drivers/watchdog/rti_wdt.c | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
> index 99168d0cad03..f806e24e53da 100644
> --- a/drivers/watchdog/rti_wdt.c
> +++ b/drivers/watchdog/rti_wdt.c
> @@ -186,14 +186,6 @@ static int rti_wdt_probe(struct udevice *dev)
>  
>  	priv->clk_hz = clk_get_rate(&clk);
>  
> -	/*
> -	 * If watchdog is running at 32k clock, it is not accurate.
> -	 * Adjust frequency down in this case so that it does not expire
> -	 * earlier than expected.
> -	 */
> -	if (priv->clk_hz < 32768)
> -		priv->clk_hz = priv->clk_hz * 9 / 10;
> -
>  	return 0;
>  }
>  

Makes sense when the kernel is updated to a stable version that contains
"watchdog: rti_wdt: Set min_hw_heartbeat_ms to accommodate a safety
margin" because the intention of this change was "to have comparable
preset values for both drivers".

Heads up for my colleagues (you already use such a kernel) and a

Reviewed-by: Jan Kiszka <jan.kiszka at siemens.com>

for this here.

Jan

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