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Message-ID: <bea41e17-0269-d88e-fd22-ad5c5a4b8dac@roeck-us.net>
Date: Tue, 25 Oct 2022 07:21:34 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Andrej Picej <andrej.picej@...ik.com>,
linux-watchdog@...r.kernel.org
Cc: wim@...ux-watchdog.org, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org, shawnguo@...nel.org,
s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
linux-imx@....com, Anson.Huang@....com, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] watchdog: imx2_wdg: suspend watchdog in WAIT mode
On 10/25/22 00:25, Andrej Picej wrote:
> Putting device into the "Suspend-To-Idle" mode causes watchdog to
> trigger and reset the board after set watchdog timeout period elapses.
>
s/reset/resets/
> Introduce new device-tree property "fsl,suspend-in-wait" which suspends
> watchdog in WAIT mode. This is done by setting WDW bit in WCR
> (Watchdog Control Register) Watchdog operation is restored after exiting
'.' after ')' missing ?
> WAIT mode as expected. WAIT mode coresponds with Linux's
s/coresponds/corresponds/
> "Suspend-To-Idle".
>
> Signed-off-by: Andrej Picej <andrej.picej@...ik.com>
> Reviewed-by: Fabio Estevam <festevam@...il.com>
> ---
> Changes in v2:
> - validate the property with compatible string, as this functionality
> is not supported by all devices.
> ---
> drivers/watchdog/imx2_wdt.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index d0c5d47ddede..dd9866c6f1e5 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -35,6 +35,7 @@
>
> #define IMX2_WDT_WCR 0x00 /* Control Register */
> #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
> +#define IMX2_WDT_WCR_WDW BIT(7) /* -> Watchdog disable for WAIT */
> #define IMX2_WDT_WCR_WDA BIT(5) /* -> External Reset WDOG_B */
> #define IMX2_WDT_WCR_SRS BIT(4) /* -> Software Reset Signal */
> #define IMX2_WDT_WCR_WRE BIT(3) /* -> WDOG Reset Enable */
> @@ -67,6 +68,27 @@ struct imx2_wdt_device {
> bool ext_reset;
> bool clk_is_on;
> bool no_ping;
> + bool sleep_wait;
> +};
> +
> +static const char * const wdw_boards[] __initconst = {
> + "fsl,imx25-wdt",
> + "fsl,imx35-wdt",
> + "fsl,imx50-wdt",
> + "fsl,imx51-wdt",
> + "fsl,imx53-wdt",
> + "fsl,imx6q-wdt",
> + "fsl,imx6sl-wdt",
> + "fsl,imx6sll-wdt",
> + "fsl,imx6sx-wdt",
> + "fsl,imx6ul-wdt",
> + "fsl,imx7d-wdt",
> + "fsl,imx8mm-wdt",
> + "fsl,imx8mn-wdt",
> + "fsl,imx8mp-wdt",
> + "fsl,imx8mq-wdt",
> + "fsl,vf610-wdt",
> + NULL
> };
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -129,6 +151,9 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog)
>
> /* Suspend timer in low power mode, write once-only */
> val |= IMX2_WDT_WCR_WDZST;
> + /* Suspend timer in low power WAIT mode, write once-only */
> + if (wdev->sleep_wait)
> + val |= IMX2_WDT_WCR_WDW;
> /* Strip the old watchdog Time-Out value */
> val &= ~IMX2_WDT_WCR_WT;
> /* Generate internal chip-level reset if WDOG times out */
> @@ -313,6 +338,18 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>
> wdev->ext_reset = of_property_read_bool(dev->of_node,
> "fsl,ext-reset-output");
> +
> + if (of_property_read_bool(dev->of_node, "fsl,suspend-in-wait"))
> + if (of_device_compatible_match(dev->of_node, wdw_boards))
> + wdev->sleep_wait = 1;
Since sleep_wait is bool:
wdev->sleep_wait = true;
> + else {
> + dev_warn(dev, "Warning: Suspending watchdog during " \
> + "WAIT mode is not supported for this device.\n");
Do not split strings. "Warning:" is redundant. Please handle the error first.
> + wdev->sleep_wait = 0;
Unnecessary; false by default. Also, this should fail and return -EINVAL.
Devicetree files should be correct, and warning messages tend to be ignored.
> + }
All branches of if/else need to wither use {} or no {}.
> + else
> + wdev->sleep_wait = 0;
> +
Unnecessary.
I would suggest to replace the above code with something like
if (of_property_read_bool(dev->of_node, "fsl,suspend-in-wait")) {
if (!of_device_compatible_match(dev->of_node, wdw_boards)) {
dev_err(dev, "Suspending watchdog in WAIT mode is not supported for this device\n");
return -EINVAL;
}
wdev->sleep_wait = true;
}
> /*
> * The i.MX7D doesn't support low power mode, so we need to ping the watchdog
> * during suspend.
I still wonder how that interacts with fsl,suspend-in-wait, but since we have a
property for that we can leave that for someone else to find out. Maybe add a
comment explaining that interaction with "fsl,suspend-in-wait" is unknown.
Thanks,
Guenter
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