Commit 6371593f authored by Jacky Bai's avatar Jacky Bai Committed by Wim Van Sebroeck
Browse files

watchdog: imx7ulp: Add explict memory barrier for unlock sequence 



When reconfiguring the WDOG Timer of i.MX7ULP, there is a certain
probability causes it to reset. The reason is that the CMD32EN of the
WDOG Timer of i.MX7ULP is disabled in bootloader. The unlock sequence
are two 16-bit writes to the CNT register within 16 bus clocks. Adding
mb() is to guarantee that two 16-bit writes are finished within 16 bus
clocks. Memory barriers cannot be added between these two 16-bit writes
so that writel_relaxed is used.

Suggested-by: default avatarYe Li <ye.li@nxp.com>
Signed-off-by: default avatarJacky Bai <ping.bai@nxp.com>
Signed-off-by: default avatarAlice Guo <alice.guo@nxp.com>
Reviewed-by: default avatarYe Li <ye.li@nxp.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220825083256.14565-3-alice.guo@oss.nxp.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@linux-watchdog.org>
parent f1826833

drivers/watchdog/imx7ulp_wdt.c

+4 −0
Original line number Diff line number Diff line
@@ -179,9 +179,13 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout) 
	int ret;



	local_irq_disable();



	mb();

	/* unlock the wdog for reconfiguration */

	writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);

	writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);

	mb();



	ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK);

	if (ret)

		goto init_out;