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Message-ID: <1badfe10-7f5f-9197-6d10-e34a586046df@norik.com>
Date: Wed, 26 Oct 2022 08:59:15 +0200
From: Andrej Picej <andrej.picej@...ik.com>
To: Guenter Roeck <linux@...ck-us.net>, 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 25. 10. 22 16:21, Guenter Roeck wrote:
> 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/
>
Will fix this in v3, thank you.
>> "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;
> }
OK, this look cleaner, will use this, thanks.
>
>> /*
>> * 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.
I'm assuming that i.MX7D doesn't enter any of low-power modes including
WAIT mode. If this is the case the watchdog wouldn't get disabled.
Anyway, I will add a short comment regarding the unknown behaviour of
this property with i.MX7D device.
Best regards,
Andrej
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