Messages in this thread Patch in this message |  | | From | "Alice Guo (OSS)" <> | Subject | [PATCH v2 2/7] watchdog: imx7ulp: Add explict memory barrier for unlock sequence | Date | Thu, 25 Aug 2022 16:32:51 +0800 |
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From: Jacky Bai <ping.bai@nxp.com>
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: Ye Li <ye.li@nxp.com> Signed-off-by: Jacky Bai <ping.bai@nxp.com> Signed-off-by: Alice Guo <alice.guo@nxp.com> Reviewed-by: Ye Li <ye.li@nxp.com> ---
Changes for v2: - add the reason why memory barriers are added for unlock sequence in commit log
drivers/watchdog/imx7ulp_wdt.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c index 014f497ea0dc..b8ac0cb04d2f 100644 --- a/drivers/watchdog/imx7ulp_wdt.c +++ b/drivers/watchdog/imx7ulp_wdt.c @@ -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; -- 2.17.1
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