From da3e515024ba32aaf0d524518ce39a8fb77332cd Mon Sep 17 00:00:00 2001 From: Nick Bowler Date: Fri, 15 Jul 2011 11:04:01 -0400 Subject: [PATCH] watchdog: sp805: Don't write 0 to the load value register. At least on the Versatile Express' V2M, calling wdt_disable followed by wdt_enable, for instance by running the following sequence: echo V > /dev/watchdog; echo V > /dev/watchdog results in an immediate reset. The wdt_disable function writes 0 to the load register; while the watchdog interrupts are disabled at this point, this special value is defined to trigger an interrupt immediately. It appears that in this instance, the reset happens when the interrupts are subsequently enabled by wdt_enable. Putting in a short delay after writing a new load value in wdt_enable solves the issue, but it seems cleaner to simply never write 0 to the load register at all: according to the hardware docs, writing 0 to the control register suffices to stop the counter, and the write of 0 to the load register is questionable anyway since this register resets to 0xffffffff. Signed-off-by: Nick Bowler Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/sp805_wdt.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c index 0d80e08b6439..c1e099aa57f3 100644 --- a/drivers/watchdog/sp805_wdt.c +++ b/drivers/watchdog/sp805_wdt.c @@ -144,7 +144,6 @@ static void wdt_disable(void) writel(UNLOCK, wdt->base + WDTLOCK); writel(0, wdt->base + WDTCONTROL); - writel(0, wdt->base + WDTLOAD); writel(LOCK, wdt->base + WDTLOCK); spin_unlock(&wdt->lock); -- 2.20.1