Re: [PATCH 1/3] hwmon: (gpd-fan): remove global variable gpd_driver_priv

[Guenter Roeck]

On 5/21/26 22:50, Pei Xiao wrote:
> After all, using the global variable |gpd_driver_priv|
> does not comply with driver development specifications.

I had marked this patch "changes requested", though I don't recall
the reason. Comment inline. Please fix and resubmit, together with
the next patch of the series but excluding the third patch.

Thanks,
Guenter

>   Friendly ping.
>
> Pei.
> Thanks!
> 在 2026/4/5 16:40, Pei Xiao 写道:
> > Replace the global state gpd_driver_priv with per-device private data
> > (struct gpd_fan_data) allocated in probe. This allows the driver to
> > support multiple instances in the future and aligns with kernel best
> > practices.
> >
> > Signed-off-by: Pei Xiao <xiaopei01@xxxxxxxxxx>
> > ---
> >   drivers/hwmon/gpd-fan.c | 211 ++++++++++++++++++++++------------------
> >   1 file changed, 116 insertions(+), 95 deletions(-)
> >
> > diff --git a/drivers/hwmon/gpd-fan.c b/drivers/hwmon/gpd-fan.c
> > index 80de5f20781e..5a9d07cd29ab 100644
> > --- a/drivers/hwmon/gpd-fan.c
> > +++ b/drivers/hwmon/gpd-fan.c
> > @@ -40,12 +40,11 @@ enum FAN_PWM_ENABLE {
> >   	AUTOMATIC	= 2,
> >   };
> >   
> > -static struct {
> > +struct gpd_fan_data {
> >   	enum FAN_PWM_ENABLE pwm_enable;
> >   	u8 pwm_value;
> > -
> >   	const struct gpd_fan_drvdata *drvdata;
> > -} gpd_driver_priv;
> > +};
> >   
> >   struct gpd_fan_drvdata {
> >   	const char *board_name; // Board name for module param comparison
> > @@ -249,10 +248,10 @@ static const struct gpd_fan_drvdata *gpd_module_drvdata[] = {
> >   };
> >   
> >   // Helper functions to handle EC read/write
> > -static void gpd_ecram_read(u16 offset, u8 *val)
> > +static void gpd_ecram_read(const struct gpd_fan_drvdata *drvdata, u16 offset, u8 *val)
> >   {
> > -	u16 addr_port = gpd_driver_priv.drvdata->addr_port;
> > -	u16 data_port = gpd_driver_priv.drvdata->data_port;
> > +	u16 addr_port = drvdata->addr_port;
> > +	u16 data_port = drvdata->data_port;
> >   
> >   	outb(0x2E, addr_port);
> >   	outb(0x11, data_port);
> > @@ -270,10 +269,10 @@ static void gpd_ecram_read(u16 offset, u8 *val)
> >   	*val = inb(data_port);
> >   }
> >   
> > -static void gpd_ecram_write(u16 offset, u8 value)
> > +static void gpd_ecram_write(const struct gpd_fan_drvdata *drvdata, u16 offset, u8 value)
> >   {
> > -	u16 addr_port = gpd_driver_priv.drvdata->addr_port;
> > -	u16 data_port = gpd_driver_priv.drvdata->data_port;
> > +	u16 addr_port = drvdata->addr_port;
> > +	u16 data_port = drvdata->data_port;
> >   
> >   	outb(0x2E, addr_port);
> >   	outb(0x11, data_port);
> > @@ -291,198 +290,198 @@ static void gpd_ecram_write(u16 offset, u8 value)
> >   	outb(value, data_port);
> >   }
> >   
> > -static int gpd_generic_read_rpm(void)
> > +static int gpd_generic_read_rpm(struct gpd_fan_data *data)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   	u8 high, low;
> >   
> > -	gpd_ecram_read(drvdata->rpm_read, &high);
> > -	gpd_ecram_read(drvdata->rpm_read + 1, &low);
> > +	gpd_ecram_read(drvdata, drvdata->rpm_read, &high);
> > +	gpd_ecram_read(drvdata, drvdata->rpm_read + 1, &low);
> >   
> >   	return (u16)high << 8 | low;
> >   }
> >   
> > -static int gpd_wm2_read_rpm(void)
> > +static int gpd_wm2_read_rpm(struct gpd_fan_data *data)
> >   {
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> > +
> >   	for (u16 pwm_ctr_offset = GPD_PWM_CTR_OFFSET;
> >   	     pwm_ctr_offset <= GPD_PWM_CTR_OFFSET + 2; pwm_ctr_offset++) {
> >   		u8 PWMCTR;
> >   
> > -		gpd_ecram_read(pwm_ctr_offset, &PWMCTR);
> > +		gpd_ecram_read(drvdata, pwm_ctr_offset, &PWMCTR);
> >   
> >   		if (PWMCTR != 0xB8)
> > -			gpd_ecram_write(pwm_ctr_offset, 0xB8);
> > +			gpd_ecram_write(drvdata, pwm_ctr_offset, 0xB8);
> >   	}
> >   
> > -	return gpd_generic_read_rpm();
> > +	return gpd_generic_read_rpm(data);
> >   }
> >   
> >   // Read value for fan1_input
> > -static int gpd_read_rpm(void)
> > +static int gpd_read_rpm(struct gpd_fan_data *data)
> >   {
> > -	switch (gpd_driver_priv.drvdata->board) {
> > +	switch (data->drvdata->board) {
> >   	case win4_6800u:
> >   	case win_mini:
> >   	case duo:
> >   	case mpc2:
> > -		return gpd_generic_read_rpm();
> > +		return gpd_generic_read_rpm(data);
> >   	case win_max_2:
> > -		return gpd_wm2_read_rpm();
> > +		return gpd_wm2_read_rpm(data);
> >   	}
> >   
> >   	return 0;
> >   }
> >   
> > -static int gpd_wm2_read_pwm(void)
> > +static int gpd_wm2_read_pwm(struct gpd_fan_data *data)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   	u8 var;
> >   
> > -	gpd_ecram_read(drvdata->pwm_write, &var);
> > +	gpd_ecram_read(drvdata, drvdata->pwm_write, &var);
> >   
> >   	// Match gpd_generic_write_pwm(u8) below
> >   	return DIV_ROUND_CLOSEST((var - 1) * 255, (drvdata->pwm_max - 1));
> >   }
> >   
> >   // Read value for pwm1
> > -static int gpd_read_pwm(void)
> > +static int gpd_read_pwm(struct gpd_fan_data *data)
> >   {
> > -	switch (gpd_driver_priv.drvdata->board) {
> > +	switch (data->drvdata->board) {
> >   	case win_mini:
> >   	case duo:
> >   	case win4_6800u:
> >   	case mpc2:
> > -		switch (gpd_driver_priv.pwm_enable) {
> > +		switch (data->pwm_enable) {
> >   		case DISABLE:
> >   			return 255;
> >   		case MANUAL:
> > -			return gpd_driver_priv.pwm_value;
> > +			return data->pwm_value;
> >   		case AUTOMATIC:
> >   			return -EOPNOTSUPP;
> >   		}
> >   		break;
> >   	case win_max_2:
> > -		return gpd_wm2_read_pwm();
> > +		return gpd_wm2_read_pwm(data);
> >   	}
> >   	return 0;
> >   }
> >   
> >   // PWM value's range in EC is 1 - pwm_max, cast 0 - 255 to it.
> > -static inline u8 gpd_cast_pwm_range(u8 val)
> > +static inline u8 gpd_cast_pwm_range(const struct gpd_fan_drvdata *drvdata, u8 val)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > -
> >   	return DIV_ROUND_CLOSEST(val * (drvdata->pwm_max - 1), 255) + 1;
> >   }
> >   
> > -static void gpd_generic_write_pwm(u8 val)
> > +static void gpd_generic_write_pwm(struct gpd_fan_data *data, u8 val)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   	u8 pwm_reg;
> >   
> > -	pwm_reg = gpd_cast_pwm_range(val);
> > -	gpd_ecram_write(drvdata->pwm_write, pwm_reg);
> > +	pwm_reg = gpd_cast_pwm_range(drvdata, val);
> > +	gpd_ecram_write(drvdata, drvdata->pwm_write, pwm_reg);
> >   }
> >   
> > -static void gpd_duo_write_pwm(u8 val)
> > +static void gpd_duo_write_pwm(struct gpd_fan_data *data, u8 val)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   	u8 pwm_reg;
> >   
> > -	pwm_reg = gpd_cast_pwm_range(val);
> > -	gpd_ecram_write(drvdata->pwm_write, pwm_reg);
> > -	gpd_ecram_write(drvdata->pwm_write + 1, pwm_reg);
> > +	pwm_reg = gpd_cast_pwm_range(drvdata, val);
> > +	gpd_ecram_write(drvdata, drvdata->pwm_write, pwm_reg);
> > +	gpd_ecram_write(drvdata, drvdata->pwm_write + 1, pwm_reg);
> >   }
> >   
> >   // Write value for pwm1
> > -static int gpd_write_pwm(u8 val)
> > +static int gpd_write_pwm(struct gpd_fan_data *data, u8 val)
> >   {
> > -	if (gpd_driver_priv.pwm_enable != MANUAL)
> > +	if (data->pwm_enable != MANUAL)
> >   		return -EPERM;
> >   
> > -	switch (gpd_driver_priv.drvdata->board) {
> > +	switch (data->drvdata->board) {
> >   	case duo:
> > -		gpd_duo_write_pwm(val);
> > +		gpd_duo_write_pwm(data, val);
> >   		break;
> >   	case win_mini:
> >   	case win4_6800u:
> >   	case win_max_2:
> >   	case mpc2:
> > -		gpd_generic_write_pwm(val);
> > +		gpd_generic_write_pwm(data, val);
> >   		break;
> >   	}
> >   
> >   	return 0;
> >   }
> >   
> > -static void gpd_win_mini_set_pwm_enable(enum FAN_PWM_ENABLE pwm_enable)
> > +static void gpd_win_mini_set_pwm_enable(struct gpd_fan_data *data, enum FAN_PWM_ENABLE pwm_enable)
> >   {
> >   	switch (pwm_enable) {
> >   	case DISABLE:
> > -		gpd_generic_write_pwm(255);
> > +		gpd_generic_write_pwm(data, 255);
> >   		break;
> >   	case MANUAL:
> > -		gpd_generic_write_pwm(gpd_driver_priv.pwm_value);
> > +		gpd_generic_write_pwm(data, data->pwm_value);
> >   		break;
> >   	case AUTOMATIC:
> > -		gpd_ecram_write(gpd_driver_priv.drvdata->pwm_write, 0);
> > +		gpd_ecram_write(data->drvdata, data->drvdata->pwm_write, 0);
> >   		break;
> >   	}
> >   }
> >   
> > -static void gpd_duo_set_pwm_enable(enum FAN_PWM_ENABLE pwm_enable)
> > +static void gpd_duo_set_pwm_enable(struct gpd_fan_data *data, enum FAN_PWM_ENABLE pwm_enable)
> >   {
> >   	switch (pwm_enable) {
> >   	case DISABLE:
> > -		gpd_duo_write_pwm(255);
> > +		gpd_duo_write_pwm(data, 255);
> >   		break;
> >   	case MANUAL:
> > -		gpd_duo_write_pwm(gpd_driver_priv.pwm_value);
> > +		gpd_duo_write_pwm(data, data->pwm_value);
> >   		break;
> >   	case AUTOMATIC:
> > -		gpd_ecram_write(gpd_driver_priv.drvdata->pwm_write, 0);
> > +		gpd_ecram_write(data->drvdata, data->drvdata->pwm_write, 0);
> >   		break;
> >   	}
> >   }
> >   
> > -static void gpd_wm2_set_pwm_enable(enum FAN_PWM_ENABLE enable)
> > +static void gpd_wm2_set_pwm_enable(struct gpd_fan_data *data, enum FAN_PWM_ENABLE enable)
> >   {
> > -	const struct gpd_fan_drvdata *const drvdata = gpd_driver_priv.drvdata;
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   
> >   	switch (enable) {
> >   	case DISABLE:
> > -		gpd_generic_write_pwm(255);
> > -		gpd_ecram_write(drvdata->manual_control_enable, 1);
> > +		gpd_generic_write_pwm(data, 255);
> > +		gpd_ecram_write(drvdata, drvdata->manual_control_enable, 1);
> >   		break;
> >   	case MANUAL:
> > -		gpd_generic_write_pwm(gpd_driver_priv.pwm_value);
> > -		gpd_ecram_write(drvdata->manual_control_enable, 1);
> > +		gpd_generic_write_pwm(data, data->pwm_value);
> > +		gpd_ecram_write(drvdata, drvdata->manual_control_enable, 1);
> >   		break;
> >   	case AUTOMATIC:
> > -		gpd_ecram_write(drvdata->manual_control_enable, 0);
> > +		gpd_ecram_write(drvdata, drvdata->manual_control_enable, 0);
> >   		break;
> >   	}
> >   }
> >   
> >   // Write value for pwm1_enable
> > -static void gpd_set_pwm_enable(enum FAN_PWM_ENABLE enable)
> > +static void gpd_set_pwm_enable(struct gpd_fan_data *data, enum FAN_PWM_ENABLE enable)
> >   {
> >   	if (enable == MANUAL)
> >   		// Set pwm_value to max firstly when switching to manual mode, in
> >   		// consideration of device safety.
> > -		gpd_driver_priv.pwm_value = 255;
> > +		data->pwm_value = 255;
> >   
> > -	switch (gpd_driver_priv.drvdata->board) {
> > +	switch (data->drvdata->board) {
> >   	case win_mini:
> >   	case win4_6800u:
> >   	case mpc2:
> > -		gpd_win_mini_set_pwm_enable(enable);
> > +		gpd_win_mini_set_pwm_enable(data, enable);
> >   		break;
> >   	case duo:
> > -		gpd_duo_set_pwm_enable(enable);
> > +		gpd_duo_set_pwm_enable(data, enable);
> >   		break;
> >   	case win_max_2:
> > -		gpd_wm2_set_pwm_enable(enable);
> > +		gpd_wm2_set_pwm_enable(data, enable);
> >   		break;
> >   	}
> >   }
> > @@ -505,15 +504,16 @@ static umode_t gpd_fan_hwmon_is_visible(__always_unused const void *drvdata,
> >   	return 0;
> >   }
> >   
> > -static int gpd_fan_hwmon_read(__always_unused struct device *dev,
> > +static int gpd_fan_hwmon_read(struct device *dev,
> >   			      enum hwmon_sensor_types type, u32 attr,
> >   			      __always_unused int channel, long *val)
> >   {
> > +	struct gpd_fan_data *data = dev_get_drvdata(dev);
> >   	int ret;
> >   
> >   	if (type == hwmon_fan) {
> >   		if (attr == hwmon_fan_input) {
> > -			ret = gpd_read_rpm();
> > +			ret = gpd_read_rpm(data);
> >   
> >   			if (ret < 0)
> >   				return ret;
> > @@ -524,10 +524,10 @@ static int gpd_fan_hwmon_read(__always_unused struct device *dev,
> >   	} else if (type == hwmon_pwm) {
> >   		switch (attr) {
> >   		case hwmon_pwm_enable:
> > -			*val = gpd_driver_priv.pwm_enable;
> > +			*val = data->pwm_enable;
> >   			return 0;
> >   		case hwmon_pwm_input:
> > -			ret = gpd_read_pwm();
> > +			ret = gpd_read_pwm(data);
> >   
> >   			if (ret < 0)
> >   				return ret;
> > @@ -540,27 +540,29 @@ static int gpd_fan_hwmon_read(__always_unused struct device *dev,
> >   	return -EOPNOTSUPP;
> >   }
> >   
> > -static int gpd_fan_hwmon_write(__always_unused struct device *dev,
> > +static int gpd_fan_hwmon_write(struct device *dev,
> >   			       enum hwmon_sensor_types type, u32 attr,
> >   			       __always_unused int channel, long val)
> >   {
> > +	struct gpd_fan_data *data = dev_get_drvdata(dev);
> > +
> >   	if (type == hwmon_pwm) {
> >   		switch (attr) {
> >   		case hwmon_pwm_enable:
> >   			if (!in_range(val, 0, 3))
> >   				return -EINVAL;
> >   
> > -			gpd_driver_priv.pwm_enable = val;
> > +			data->pwm_enable = val;
> >   
> > -			gpd_set_pwm_enable(gpd_driver_priv.pwm_enable);
> > +			gpd_set_pwm_enable(data, data->pwm_enable);
> >   			return 0;
> >   		case hwmon_pwm_input:
> >   			if (!in_range(val, 0, 256))
> >   				return -EINVAL;
> >   
> > -			gpd_driver_priv.pwm_value = val;
> > +			data->pwm_value = val;
> >   
> > -			return gpd_write_pwm(val);
> > +			return gpd_write_pwm(data, val);
> >   		}
> >   	}
> >   
> > @@ -584,26 +586,27 @@ static struct hwmon_chip_info gpd_fan_chip_info = {
> >   	.info = gpd_fan_hwmon_channel_info
> >   };
> >   
> > -static void gpd_win4_init_ec(void)
> > +static void gpd_win4_init_ec(struct gpd_fan_data *data)
> >   {
> > +	const struct gpd_fan_drvdata *drvdata = data->drvdata;
> >   	u8 chip_id, chip_ver;
> >   
> > -	gpd_ecram_read(0x2000, &chip_id);
> > +	gpd_ecram_read(drvdata, 0x2000, &chip_id);
> >   
> >   	if (chip_id == 0x55) {
> > -		gpd_ecram_read(0x1060, &chip_ver);
> > -		gpd_ecram_write(0x1060, chip_ver | 0x80);
> > +		gpd_ecram_read(drvdata, 0x1060, &chip_ver);
> > +		gpd_ecram_write(drvdata, 0x1060, chip_ver | 0x80);
> >   	}
> >   }
> >   
> > -static void gpd_init_ec(void)
> > +static void gpd_init_ec(struct gpd_fan_data *data)
> >   {
> >   	// The buggy firmware won't initialize EC properly on boot.
> >   	// Before its initialization, reading RPM will always return 0,
> >   	// and writing PWM will have no effect.
> >   	// Initialize it manually on driver load.
> > -	if (gpd_driver_priv.drvdata->board == win4_6800u)
> > -		gpd_win4_init_ec();
> > +	if (data->drvdata->board == win4_6800u)
> > +		gpd_win4_init_ec(data);
> >   }
> >   
> >   static int gpd_fan_probe(struct platform_device *pdev)
> > @@ -611,7 +614,9 @@ static int gpd_fan_probe(struct platform_device *pdev)
> >   	struct device *dev = &pdev->dev;
> >   	const struct resource *region;
> >   	const struct resource *res;
> > -	const struct device *hwdev;
> > +	struct device *hwdev;
> > +	struct gpd_fan_data *data;
> > +	const struct gpd_fan_drvdata **match_ptr;
> >   
> >   	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
> >   	if (!res)
> > @@ -624,24 +629,42 @@ static int gpd_fan_probe(struct platform_device *pdev)
> >   		return dev_err_probe(dev, -EBUSY,
> >   				     "Failed to request region\n");
> >   
> > +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +	if (!data)
> > +		return -ENOMEM;
> > +
> > +	match_ptr = dev_get_platdata(dev);
> > +	if (!match_ptr)
> > +		return -EINVAL;
> > +	data->drvdata = *match_ptr;
> > +
> > +	data->pwm_enable = AUTOMATIC;
> > +	data->pwm_value = 255;
> > +
> > +	dev_set_drvdata(dev, data);
> > +
> > +	gpd_init_ec(data);
> > +
> >   	hwdev = devm_hwmon_device_register_with_info(dev,
> >   						     DRIVER_NAME,
> > -						     NULL,
> > +						     data,
> >   						     &gpd_fan_chip_info,
> >   						     NULL);
> >   	if (IS_ERR(hwdev))
> >   		return dev_err_probe(dev, PTR_ERR(hwdev),
> >   				     "Failed to register hwmon device\n");
> >   
> > -	gpd_init_ec();
> > -

This suspiciously looks like a bug fix which is not mentioned in the
commit description. Either explain why it is now needed before hwmon
registration and why that was not the case before, or submit as separate
bug fix.

> >   	return 0;
> >   }
> >   
> > -static void gpd_fan_remove(__always_unused struct platform_device *pdev)
> > +static void gpd_fan_remove(struct platform_device *pdev)
> >   {
> > -	gpd_driver_priv.pwm_enable = AUTOMATIC;
> > -	gpd_set_pwm_enable(AUTOMATIC);
> > +	struct gpd_fan_data *data = dev_get_drvdata(&pdev->dev);
> > +
> > +	if (data) {
> > +		data->pwm_enable = AUTOMATIC;
> > +		gpd_set_pwm_enable(data, AUTOMATIC);
> > +	}
> >   }
> >   
> >   static struct platform_driver gpd_fan_driver = {
> > @@ -668,6 +691,7 @@ static int __init gpd_fan_init(void)
> >   	if (!match) {
> >   		const struct dmi_system_id *dmi_match =
> >   			dmi_first_match(dmi_table);
> > +
> >   		if (dmi_match)
> >   			match = dmi_match->driver_data;
> >   	}
> > @@ -675,10 +699,6 @@ static int __init gpd_fan_init(void)
> >   	if (!match)
> >   		return -ENODEV;
> >   
> > -	gpd_driver_priv.pwm_enable = AUTOMATIC;
> > -	gpd_driver_priv.pwm_value = 255;
> > -	gpd_driver_priv.drvdata = match;
> > -
> >   	struct resource gpd_fan_resources[] = {
> >   		{
> >   			.start = match->addr_port,
> > @@ -690,7 +710,8 @@ static int __init gpd_fan_init(void)
> >   	gpd_fan_platform_device = platform_create_bundle(&gpd_fan_driver,
> >   							 gpd_fan_probe,
> >   							 gpd_fan_resources,
> > -							 1, NULL, 0);
> > +							 1,
> > +							 &match, sizeof(match));

Why &match instead of just match ? match is a pointer to driver_data which itself
is a pointer. Passing a pointer to a pointer just to dereference it in the probe
function doesn't make sense to me.

> >   
> >   	if (IS_ERR(gpd_fan_platform_device)) {
> >   		pr_warn("Failed to create platform device\n");