On Mon, 2025-02-17 at 21:33 -0800, Guenter Roeck wrote:

On 2/17/25 19:16, Heyi Guo wrote:

quoted

Aspeed watchdog uses counting down logic, so the value set to register
should be the value of subtracting pretimeout from total timeout.

Fixes: 9ec0b7e06835 ("watchdog: aspeed: Enable pre-timeout interrupt")

Signed-off-by: Heyi Guo <redacted>

Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@codeconstruct.com.au>
Cc: Eddie James <eajames@linux.ibm.com>
---
  drivers/watchdog/aspeed_wdt.c | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index b4773a6aaf8c..520d8aba12a5 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c

@@ -187,6 +187,13 @@ static int aspeed_wdt_set_pretimeout(struct watchdog_device *wdd,

        u32 actual = pretimeout * WDT_RATE_1MHZ;
        u32 s = wdt->cfg->irq_shift;
        u32 m = wdt->cfg->irq_mask;
+       u32 reload = readl(wdt->base + WDT_RELOAD_VALUE);
+

It is unusual to use a register value here and not the configured timeout
value. I would have assumed that pretimeout is compared against wdt->timout,
not against the register value, and that the multiplication with WDT_RATE_1MHZ
is done after validation. This needs an explanation.

+1

quoted

+       if (actual >= reload)
+               return -EINVAL;
+

On top of that, you'll also need to explain why watchdog_pretimeout_invalid()
and with it the validation in watchdog_set_pretimeout() does not work for this
watchdog and why this extra validation is necessary.

+1 as well.

Further, the logic looks broken regardless for the AST2400 where
there's no pretimeout support. aspeed_wdt_set_pretimeout() should error
out if wdt->cfg->irq_mask is 0.

Andrew