Re: PROBLEM: NCT6775: suspend doesn't work after updating to Linux 5.19

[Zev Weiss <zev@xxxxxxxxxxxxxxxxx>]

On Tue, Aug 09, 2022 at 01:27:48PM PDT, Zoltán Kővágó wrote:
> Hi,
>
> [1.] One line summary of the problem:
> NCT6775: suspend doesn't work after updating to Linux 5.19
>
> [2.] Full description of the problem/report:
> After updating my kernel from 5.18.11 to 5.19, I've noticed that 
> resuming after suspend no longer works: fans start up, then about a 
> second later, the computer just shuts down, leaving the USB ports 
> powered up (normally it turns them off on shutdown). The screens don't 
> turn on during this timeframe, so I can't see any useful log messages.
>
> Bisecting between 5.18 (where it still worked) and 5.19 lead me to 
> commit c3963bc0a0cf9ecb205a9d4976eb92b6df2fa3fd "hwmon: (nct6775) 
> Split core and platform driver" which looks like a refactor commit, 
> but apparently it broke something.

Hi Zoltán,

Thanks for the thorough bug report.  You're right that that commit was 
essentially just a refactor, though there was one slight change to the 
nct6775_suspend() function introduced during the review process that 
may perhaps have had some subtle unintended side-effects.

Can you test the following patch and report if it resolves the problem?


Thanks,
Zev

diff --git a/drivers/hwmon/nct6775-core.c b/drivers/hwmon/nct6775-core.c
index 446964cbae4c..da9ec6983e13 100644
--- a/drivers/hwmon/nct6775-core.c
+++ b/drivers/hwmon/nct6775-core.c
@@ -1480,7 +1480,7 @@ static int nct6775_update_pwm_limits(struct device *dev)
 	return 0;
 }
 
-static struct nct6775_data *nct6775_update_device(struct device *dev)
+struct nct6775_data *nct6775_update_device(struct device *dev)
 {
 	struct nct6775_data *data = dev_get_drvdata(dev);
 	int i, j, err = 0;
@@ -1615,6 +1615,7 @@ static struct nct6775_data *nct6775_update_device(struct device *dev)
 	mutex_unlock(&data->update_lock);
 	return err ? ERR_PTR(err) : data;
 }
+EXPORT_SYMBOL_GPL(nct6775_update_device);
 
 /*
  * Sysfs callback functions
diff --git a/drivers/hwmon/nct6775-platform.c b/drivers/hwmon/nct6775-platform.c
index ab30437221ce..41c97cfacfb8 100644
--- a/drivers/hwmon/nct6775-platform.c
+++ b/drivers/hwmon/nct6775-platform.c
@@ -359,7 +359,7 @@ static int __maybe_unused nct6775_suspend(struct device *dev)
 {
 	int err;
 	u16 tmp;
-	struct nct6775_data *data = dev_get_drvdata(dev);
+	struct nct6775_data *data = nct6775_update_device(dev);
 
 	if (IS_ERR(data))
 		return PTR_ERR(data);
diff --git a/drivers/hwmon/nct6775.h b/drivers/hwmon/nct6775.h
index 93f708148e65..be41848c3cd2 100644
--- a/drivers/hwmon/nct6775.h
+++ b/drivers/hwmon/nct6775.h
@@ -196,6 +196,8 @@ static inline int nct6775_write_value(struct nct6775_data *data, u16 reg, u16 va
 	return regmap_write(data->regmap, reg, value);
 }
 
+struct nct6775_data *nct6775_update_device(struct device *dev);
+
 bool nct6775_reg_is_word_sized(struct nct6775_data *data, u16 reg);
 int nct6775_probe(struct device *dev, struct nct6775_data *data,
 		  const struct regmap_config *regmapcfg);