diff mbox

[v3,7/8] hwmon: pwm-fan: Read PWM FAN configuration from device tree

Message ID 1423241948-31981-8-git-send-email-l.majewski@samsung.com (mailing list archive)
State Superseded, archived
Delegated to: Eduardo Valentin
Headers show

Commit Message

Lukasz Majewski Feb. 6, 2015, 4:59 p.m. UTC
This patch provides code for reading PWM FAN configuration data via
device tree. The pwm-fan can work with full speed when configuration
is not provided. However, errors are propagated when wrong DT bindings
are found.
Additionally the struct pwm_fan_ctx has been extended.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
---
Changes for v2:
- Rename pwm_fan_max_states to pwm_fan_cooling_levels
- Moving pwm_fan_of_get_cooling_data() call after setting end enabling PWM FAN
- pwm_fan_of_get_cooling_data() now can fail - preserving old behaviour
- Remove unnecessary dev_err() call
Changes for v3:
- Patch's headline has been reedited
- pwm_fan_of_get_cooling_data() return code is now being checked.
- of_property_count_elems_of_size() is now used instead of_find_property()
- More verbose patch description added
---
 drivers/hwmon/pwm-fan.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

Comments

Guenter Roeck Feb. 6, 2015, 6:36 p.m. UTC | #1
On Fri, Feb 06, 2015 at 05:59:07PM +0100, Lukasz Majewski wrote:
> This patch provides code for reading PWM FAN configuration data via
> device tree. The pwm-fan can work with full speed when configuration
> is not provided. However, errors are propagated when wrong DT bindings
> are found.
> Additionally the struct pwm_fan_ctx has been extended.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
> ---
> Changes for v2:
> - Rename pwm_fan_max_states to pwm_fan_cooling_levels
> - Moving pwm_fan_of_get_cooling_data() call after setting end enabling PWM FAN
> - pwm_fan_of_get_cooling_data() now can fail - preserving old behaviour
> - Remove unnecessary dev_err() call
> Changes for v3:
> - Patch's headline has been reedited
> - pwm_fan_of_get_cooling_data() return code is now being checked.
> - of_property_count_elems_of_size() is now used instead of_find_property()
> - More verbose patch description added
> ---
>  drivers/hwmon/pwm-fan.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 53 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 870e100..f3f5843 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -30,7 +30,10 @@
>  struct pwm_fan_ctx {
>  	struct mutex lock;
>  	struct pwm_device *pwm;
> -	unsigned char pwm_value;
> +	unsigned int pwm_value;
> +	unsigned int pwm_fan_state;
> +	unsigned int pwm_fan_max_state;
> +	unsigned int *pwm_fan_cooling_levels;
>  };
>  
>  static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> @@ -100,6 +103,50 @@ static struct attribute *pwm_fan_attrs[] = {
>  
>  ATTRIBUTE_GROUPS(pwm_fan);
>  
> +int pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
> +{
> +	struct device_node *np = dev->of_node;
> +	int num, i, ret;
> +
> +	ret = of_property_count_elems_of_size(np, "cooling-levels",
> +					      sizeof(u32));
> +
> +	if (ret == -EINVAL) {
> +		dev_err(dev, "Property 'cooling-levels' not found\n");
> +		return 0;

Returning 0 is obviously not an error, otherwise you would not return 0 here.
So dev_err is wrong. Also, the message itself is wrong; the property may
well be there but have a wrong size.

> +	}
> +
> +	if (ret <= 0) {
> +		dev_err(dev, "Wrong data!\n");
> +		return ret;
> +	}

This will result in the driver failing to load if devicetree is not configured
(of_property_count_elems_of_size will return -ENOSYS). This is not acceptable.
Also, if the call returns 0 you don't return an error but display a "Wrong data!"
error message. Either it is an error or it is not, but not both.

Guenter
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Lukasz Majewski Feb. 8, 2015, 9:36 p.m. UTC | #2
On Fri, 6 Feb 2015 10:36:57 -0800
Guenter Roeck <linux@roeck-us.net> wrote:

> On Fri, Feb 06, 2015 at 05:59:07PM +0100, Lukasz Majewski wrote:
> > This patch provides code for reading PWM FAN configuration data via
> > device tree. The pwm-fan can work with full speed when configuration
> > is not provided. However, errors are propagated when wrong DT
> > bindings are found.
> > Additionally the struct pwm_fan_ctx has been extended.
> > 
> > Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
> > ---
> > Changes for v2:
> > - Rename pwm_fan_max_states to pwm_fan_cooling_levels
> > - Moving pwm_fan_of_get_cooling_data() call after setting end
> > enabling PWM FAN
> > - pwm_fan_of_get_cooling_data() now can fail - preserving old
> > behaviour
> > - Remove unnecessary dev_err() call
> > Changes for v3:
> > - Patch's headline has been reedited
> > - pwm_fan_of_get_cooling_data() return code is now being checked.
> > - of_property_count_elems_of_size() is now used instead
> > of_find_property()
> > - More verbose patch description added
> > ---
> >  drivers/hwmon/pwm-fan.c | 54
> > ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed,
> > 53 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> > index 870e100..f3f5843 100644
> > --- a/drivers/hwmon/pwm-fan.c
> > +++ b/drivers/hwmon/pwm-fan.c
> > @@ -30,7 +30,10 @@
> >  struct pwm_fan_ctx {
> >  	struct mutex lock;
> >  	struct pwm_device *pwm;
> > -	unsigned char pwm_value;
> > +	unsigned int pwm_value;
> > +	unsigned int pwm_fan_state;
> > +	unsigned int pwm_fan_max_state;
> > +	unsigned int *pwm_fan_cooling_levels;
> >  };
> >  
> >  static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> > @@ -100,6 +103,50 @@ static struct attribute *pwm_fan_attrs[] = {
> >  
> >  ATTRIBUTE_GROUPS(pwm_fan);
> >  
> > +int pwm_fan_of_get_cooling_data(struct device *dev, struct
> > pwm_fan_ctx *ctx) +{
> > +	struct device_node *np = dev->of_node;
> > +	int num, i, ret;
> > +
> > +	ret = of_property_count_elems_of_size(np, "cooling-levels",
> > +					      sizeof(u32));
> > +
> > +	if (ret == -EINVAL) {
> > +		dev_err(dev, "Property 'cooling-levels' not
> > found\n");
> > +		return 0;
> 
> Returning 0 is obviously not an error, otherwise you would not return
> 0 here. So dev_err is wrong.

pr_info would be more appropriate here.

> Also, the message itself is wrong; the
> property may well be there but have a wrong size.

As fair as I remember the -EINVAL is set only when the property is not
defined. Such situation is correct and our pwm-fan driver should work
with or without it.

> 
> > +	}
> > +
> > +	if (ret <= 0) {
> > +		dev_err(dev, "Wrong data!\n");
> > +		return ret;
> > +	}
> 
> This will result in the driver failing to load if devicetree is not
> configured (of_property_count_elems_of_size will return -ENOSYS).

As you pointed out in the comment to v2:

It is OK if the "cooling-levels" is not defined in DT. However, if it
has broken definition, then we should return error. This is what we do
here.

> This is not acceptable. Also, if the call returns 0 you don't return
> an error but display a "Wrong data!" error message. Either it is an
> error or it is not, but not both.

This is an error. "cooling-levels" with zero elements is regarded as a
broken property.

> 
> Guenter

Best regards,
Lukasz Majewski
Guenter Roeck Feb. 9, 2015, 4:40 a.m. UTC | #3
On 02/08/2015 01:36 PM, Lukasz Majewski wrote:
> On Fri, 6 Feb 2015 10:36:57 -0800
> Guenter Roeck <linux@roeck-us.net> wrote:
>
>> On Fri, Feb 06, 2015 at 05:59:07PM +0100, Lukasz Majewski wrote:
>>> This patch provides code for reading PWM FAN configuration data via
>>> device tree. The pwm-fan can work with full speed when configuration
>>> is not provided. However, errors are propagated when wrong DT
>>> bindings are found.
>>> Additionally the struct pwm_fan_ctx has been extended.
>>>
>>> Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
>>> ---
>>> Changes for v2:
>>> - Rename pwm_fan_max_states to pwm_fan_cooling_levels
>>> - Moving pwm_fan_of_get_cooling_data() call after setting end
>>> enabling PWM FAN
>>> - pwm_fan_of_get_cooling_data() now can fail - preserving old
>>> behaviour
>>> - Remove unnecessary dev_err() call
>>> Changes for v3:
>>> - Patch's headline has been reedited
>>> - pwm_fan_of_get_cooling_data() return code is now being checked.
>>> - of_property_count_elems_of_size() is now used instead
>>> of_find_property()
>>> - More verbose patch description added
>>> ---
>>>   drivers/hwmon/pwm-fan.c | 54
>>> ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed,
>>> 53 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>>> index 870e100..f3f5843 100644
>>> --- a/drivers/hwmon/pwm-fan.c
>>> +++ b/drivers/hwmon/pwm-fan.c
>>> @@ -30,7 +30,10 @@
>>>   struct pwm_fan_ctx {
>>>   	struct mutex lock;
>>>   	struct pwm_device *pwm;
>>> -	unsigned char pwm_value;
>>> +	unsigned int pwm_value;
>>> +	unsigned int pwm_fan_state;
>>> +	unsigned int pwm_fan_max_state;
>>> +	unsigned int *pwm_fan_cooling_levels;
>>>   };
>>>
>>>   static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>>> @@ -100,6 +103,50 @@ static struct attribute *pwm_fan_attrs[] = {
>>>
>>>   ATTRIBUTE_GROUPS(pwm_fan);
>>>
>>> +int pwm_fan_of_get_cooling_data(struct device *dev, struct
>>> pwm_fan_ctx *ctx) +{
>>> +	struct device_node *np = dev->of_node;
>>> +	int num, i, ret;
>>> +
>>> +	ret = of_property_count_elems_of_size(np, "cooling-levels",
>>> +					      sizeof(u32));
>>> +
>>> +	if (ret == -EINVAL) {
>>> +		dev_err(dev, "Property 'cooling-levels' not
>>> found\n");
>>> +		return 0;
>>
>> Returning 0 is obviously not an error, otherwise you would not return
>> 0 here. So dev_err is wrong.
>
> pr_info would be more appropriate here.
>
>> Also, the message itself is wrong; the
>> property may well be there but have a wrong size.
>
> As fair as I remember the -EINVAL is set only when the property is not
> defined. Such situation is correct and our pwm-fan driver should work
> with or without it.
>

of_property_count_elems_of_size returns -EINVAL if np is NULL or if
there is no peoperty or prop->length % elem_size != 0, and -ENODATA
if there is no value associated with the property.

If -EINVAL is not an error, please no message. Noisy drivers are
just that, noisy.

>>
>>> +	}
>>> +
>>> +	if (ret <= 0) {
>>> +		dev_err(dev, "Wrong data!\n");
>>> +		return ret;
>>> +	}
>>
>> This will result in the driver failing to load if devicetree is not
>> configured (of_property_count_elems_of_size will return -ENOSYS).
>
> As you pointed out in the comment to v2:
>
> It is OK if the "cooling-levels" is not defined in DT. However, if it
> has broken definition, then we should return error. This is what we do
> here.
>
You don't return an error, you return 0, at least in some circumstances.

>> This is not acceptable. Also, if the call returns 0 you don't return
>> an error but display a "Wrong data!" error message. Either it is an
>> error or it is not, but not both.
>
> This is an error. "cooling-levels" with zero elements is regarded as a
> broken property.
>
It returns -ENOSYS if DT is not configured, which is still unacceptable.
And, again, if ret == 0 is an error, you should return an error code,
not display an error message and return 0.

Guenter

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diff mbox

Patch

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 870e100..f3f5843 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -30,7 +30,10 @@ 
 struct pwm_fan_ctx {
 	struct mutex lock;
 	struct pwm_device *pwm;
-	unsigned char pwm_value;
+	unsigned int pwm_value;
+	unsigned int pwm_fan_state;
+	unsigned int pwm_fan_max_state;
+	unsigned int *pwm_fan_cooling_levels;
 };
 
 static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
@@ -100,6 +103,50 @@  static struct attribute *pwm_fan_attrs[] = {
 
 ATTRIBUTE_GROUPS(pwm_fan);
 
+int pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
+{
+	struct device_node *np = dev->of_node;
+	int num, i, ret;
+
+	ret = of_property_count_elems_of_size(np, "cooling-levels",
+					      sizeof(u32));
+
+	if (ret == -EINVAL) {
+		dev_err(dev, "Property 'cooling-levels' not found\n");
+		return 0;
+	}
+
+	if (ret <= 0) {
+		dev_err(dev, "Wrong data!\n");
+		return ret;
+	}
+
+	num = ret;
+	ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
+						   GFP_KERNEL);
+	if (!ctx->pwm_fan_cooling_levels)
+		return -ENOMEM;
+
+	ret = of_property_read_u32_array(np, "cooling-levels",
+					 ctx->pwm_fan_cooling_levels, num);
+	if (ret) {
+		dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
+		return ret;
+	}
+
+	for (i = 0; i < num; i++) {
+		if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
+			dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
+				ctx->pwm_fan_cooling_levels[i], MAX_PWM);
+			return -EINVAL;
+		}
+	}
+
+	ctx->pwm_fan_max_state = num - 1;
+
+	return 0;
+}
+
 static int pwm_fan_probe(struct platform_device *pdev)
 {
 	struct device *hwmon;
@@ -145,6 +192,11 @@  static int pwm_fan_probe(struct platform_device *pdev)
 		pwm_disable(ctx->pwm);
 		return PTR_ERR(hwmon);
 	}
+
+	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
+	if (ret)
+		return ret;
+
 	return 0;
 }