| Message ID | 20240930060653.4024-1-towinchenmi@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [RESEND] watchdog: apple: Increase reset delay to 150ms | expand |
On Mon, Sep 30, 2024, at 06:06, Nick Chan wrote: > The Apple A8X SoC seems to be slowest at resetting, taking up to around > 125ms to reset. Wait 150ms to be safe here. > > Reviewed-by: Sven Peter <sven@svenpeter.dev> > Reviewed-by: Guenter Roeck <linux@roeck-us.net> > Signed-off-by: Nick Chan <towinchenmi@gmail.com> > --- > drivers/watchdog/apple_wdt.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c > index d4f739932f0b..353ecf0b04dc 100644 > --- a/drivers/watchdog/apple_wdt.c > +++ b/drivers/watchdog/apple_wdt.c > @@ -127,11 +127,11 @@ static int apple_wdt_restart(struct > watchdog_device *wdd, unsigned long mode, > /* > * Flush writes and then wait for the SoC to reset. Even though the > * reset is queued almost immediately experiments have shown that it > - * can take up to ~20-25ms until the SoC is actually reset. Just wait > - * 50ms here to be safe. > + * can take up to ~120-125ms until the SoC is actually reset. Just > + * wait 150ms here to be safe. > */ > (void)readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME); > - mdelay(50); > + mdelay(150); I think you also need to insert a barrier before the mdelay(), or turn the readl_relaxed() into a readl(), it will otherwise be bypassed by the delay. The comment is a bit confusing here as it suggests that the MMIO read is meant to serialize between the restart and the mdelay(), but the _relaxed() annotation on the readl() explicitly skips that serialization, so one of the two is wrong here. Arnd
diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c index d4f739932f0b..353ecf0b04dc 100644 --- a/drivers/watchdog/apple_wdt.c +++ b/drivers/watchdog/apple_wdt.c @@ -127,11 +127,11 @@ static int apple_wdt_restart(struct watchdog_device *wdd, unsigned long mode, /* * Flush writes and then wait for the SoC to reset. Even though the * reset is queued almost immediately experiments have shown that it - * can take up to ~20-25ms until the SoC is actually reset. Just wait - * 50ms here to be safe. + * can take up to ~120-125ms until the SoC is actually reset. Just + * wait 150ms here to be safe. */ (void)readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME); - mdelay(50); + mdelay(150); return 0; }