device property: Document how to check for the property presence

Currently it's unclear if one may or may not rely on the error codes returned from the property getters to check for the property presence. Clarify this by mass updating kernel-doc for fwnode_property_*() and device_property_*() where it's applicable.

Reported-by Guenter Roeck <[email protected]>

Closes [email protected]

Signed-off-by Andy Shevchenko <[email protected]>

---
 drivers/base/property.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

drivers/base/property.c +11 -3

index 8d9a34be57fb..bffa0070ab13 100644
@@ -38,6 +38,8 @@ EXPORT_SYMBOL_GPL(__dev_fwnode_const);
  * @propname: Name of the property
  *
  * Check if property @propname is present in the device firmware description.
+ * This function is the correct way to check that given property is present
+ * in the device firmware description.
  *
  * Return: true if property @propname is present. Otherwise, returns false.
  */

@@ -52,6 +54,10 @@ EXPORT_SYMBOL_GPL(device_property_present);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
+ * Check if property @propname is present in the firmware node description.
+ * This function is the correct way to check that given property is present
+ * in the firmware node description.
+ *
  * Return: true if property @propname is present. Otherwise, returns false.
  */
 bool fwnode_property_present(const struct fwnode_handle *fwnode,

@@ -75,9 +81,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
  * @dev: Device whose property is being checked
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the device firmware description.
+ * Use device_property_present() to check for the property presence.
  *
- * Return: true if property @propname is present. Otherwise, returns false.
+ * Return: if property @propname is true or false in the device firmware description.
  */
 bool device_property_read_bool(const struct device *dev, const char *propname)
 {

@@ -90,7 +96,9 @@ EXPORT_SYMBOL_GPL(device_property_read_bool);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the firmware description.
+ * Use fwnode_property_present() to check for the property presence.
+ *
+ * Return: if property @propname is true or false in the firmware node description.
  */
 bool fwnode_property_read_bool(const struct fwnode_handle *fwnode,
 			     const char *propname)

drivers/base/property.c +23 -0

+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -149,6 +159,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
  * It's recommended to call device_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -177,6 +189,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
  * It's recommended to call device_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -205,6 +219,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
  * It's recommended to call device_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -233,6 +249,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
  * It's recommended to call device_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,

@@ -257,6 +275,8 @@ EXPORT_SYMBOL_GPL(device_property_read_string_array);
  * Function reads property @propname from the device firmware description and
  * stores the value into @val if found. The value is checked to be a string.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,

@@ -324,6 +344,8 @@ static int fwnode_property_read_int_array(const struct fwnode_handle *fwnode,
  * It's recommended to call fwnode_property_count_u8() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -353,6 +375,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);
  * It's recommended to call fwnode_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -382,6 +406,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);
  * It's recommended to call fwnode_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -411,6 +437,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);
  * It's recommended to call fwnode_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -440,6 +468,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);
  * It's recommended to call fwnode_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,

@@ -476,6 +506,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
  * Read property @propname from the given firmware node and store the value into
  * @val if found.  The value is checked to be a string.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,

Hi Andy,

Thanks for the patch.

Quoted 60 lines · Andy Shevchenko

Currently it's unclear if one may or may not rely on the error codes returned from the property getters to check for the property presence. Clarify this by mass updating kernel-doc for fwnode_property_*() and device_property_*() where it's applicable.

Reported-by Guenter Roeck <[email protected]>

Closes [email protected]

Signed-off-by Andy Shevchenko <[email protected]>

---
 drivers/base/property.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

drivers/base/property.c +11 -3

index 8d9a34be57fb..bffa0070ab13 100644
@@ -38,6 +38,8 @@ EXPORT_SYMBOL_GPL(__dev_fwnode_const);
  * @propname: Name of the property
  *
  * Check if property @propname is present in the device firmware description.
+ * This function is the correct way to check that given property is present
+ * in the device firmware description.
  *
  * Return: true if property @propname is present. Otherwise, returns false.
  */

@@ -52,6 +54,10 @@ EXPORT_SYMBOL_GPL(device_property_present);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
+ * Check if property @propname is present in the firmware node description.
+ * This function is the correct way to check that given property is present
+ * in the firmware node description.
+ *
  * Return: true if property @propname is present. Otherwise, returns false.
  */
 bool fwnode_property_present(const struct fwnode_handle *fwnode,

@@ -75,9 +81,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
  * @dev: Device whose property is being checked
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the device firmware description.
+ * Use device_property_present() to check for the property presence.
  *
- * Return: true if property @propname is present. Otherwise, returns false.
+ * Return: if property @propname is true or false in the device firmware description.
  */
 bool device_property_read_bool(const struct device *dev, const char *propname)
 {

@@ -90,7 +96,9 @@ EXPORT_SYMBOL_GPL(device_property_read_bool);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the firmware description.
+ * Use fwnode_property_present() to check for the property presence.
+ *
+ * Return: if property @propname is true or false in the firmware node description.
  */
 bool fwnode_property_read_bool(const struct fwnode_handle *fwnode,
 			     const char *propname)

drivers/base/property.c EXPORT_SYMBOL_GPL(fwnode_property_read_bool); · line 132

Quoted 4 lines

drivers/base/property.c +1 -0

@@ -121,6 +129,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_bool);
  * It's recommended to call device_property_count_u8() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions? I don't think it belongs here.

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this. It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

Quoted 103 lines

drivers/base/property.c +23 -0

+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -149,6 +159,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
  * It's recommended to call device_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -177,6 +189,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
  * It's recommended to call device_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -205,6 +219,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
  * It's recommended to call device_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -233,6 +249,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
  * It's recommended to call device_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,

@@ -257,6 +275,8 @@ EXPORT_SYMBOL_GPL(device_property_read_string_array);
  * Function reads property @propname from the device firmware description and
  * stores the value into @val if found. The value is checked to be a string.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,

@@ -324,6 +344,8 @@ static int fwnode_property_read_int_array(const struct fwnode_handle *fwnode,
  * It's recommended to call fwnode_property_count_u8() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -353,6 +375,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);
  * It's recommended to call fwnode_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -382,6 +406,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);
  * It's recommended to call fwnode_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -411,6 +437,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);
  * It's recommended to call fwnode_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,

@@ -440,6 +468,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);
  * It's recommended to call fwnode_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,

@@ -476,6 +506,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
  * Read property @propname from the given firmware node and store the value into
  * @val if found.  The value is checked to be a string.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: %0 if the property was found (success),
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,

Signature · 3 lines

Kind regards,

Sakari Ailus

On Tue, Mar 17, 2026 at 10:08:28PM +0100, Andy Shevchenko wrote:

Quoted 1 line

+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions?

I don't think it belongs here.

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this.

It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

Quoted 1 line · Sakari Ailus

On Tue, Mar 17, 2026 at 10:08:28PM +0100, Andy Shevchenko wrote:

...

Quoted 3 lines

Quoted 1 line

+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions?

Yes, as Guenter pointed out that this has to be documented clearly.

Quoted 1 line

I don't think it belongs here.

And? What should we do then (taking into account my below comments)?

Quoted 2 lines

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this.

No, this change is exactly against this. Because using an error code that may cover not only that case is at bare minimum fragile and layering violation. APIs that require to know the implementation details are not good APIs.

Quoted 5 lines

It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

I'm against this because we have already a dedicated API to check for property presence, why do we need to have another (confusing!) way of doing the same?

Having a dedicated code may help to debug, but shouldn't be used as a main feature in my opinion.

Quoted 2 lines · Andy Shevchenko

Quoted 1 line · Sakari Ailus

On Tue, Mar 17, 2026 at 10:08:28PM +0100, Andy Shevchenko wrote:

Quoted 10 lines

Quoted 3 lines

Quoted 1 line

+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions?

Yes, as Guenter pointed out that this has to be documented clearly.

Quoted 1 line

I don't think it belongs here.

And? What should we do then (taking into account my below comments)?

Quoted 6 lines

Quoted 2 lines

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this.

No, this change is exactly against this. Because using an error code that may cover not only that case is at bare minimum fragile and layering violation. APIs that require to know the implementation details are not good APIs.

I have to say I disagree with that,

there's nothing wrong with checking
error codes if you need to.

Either way, I checked the original patch. If you really think you need to check for property presence and use default in the case the property isn't found and error out on other errors, add helper functions for the purpose instead of open-coding it all.

Quoted 10 lines

Quoted 4 lines

It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

I'm against this because we have already a dedicated API to check for property presence, why do we need to have another (confusing!) way of doing the same?

Having a dedicated code may help to debug, but shouldn't be used as a main feature in my opinion.

Quoted 3 lines · Sakari Ailus

Quoted 2 lines · Andy Shevchenko

Quoted 1 line · Sakari Ailus

On Tue, Mar 17, 2026 at 10:08:28PM +0100, Andy Shevchenko wrote:

...

Quoted 17 lines

Quoted 16 lines

Quoted 3 lines

Quoted 1 line

+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions?

Yes, as Guenter pointed out that this has to be documented clearly.

Quoted 1 line

I don't think it belongs here.

And? What should we do then (taking into account my below comments)?

Quoted 2 lines

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this.

No, this change is exactly against this. Because using an error code that may cover not only that case is at bare minimum fragile and layering violation. APIs that require to know the implementation details are not good APIs.

Quoted 1 line

I have to say I disagree with that,

And I definitely disagree with tribal knowledge based (implementation details as it's not properly documented and can't, because -EINVAL is overloaded) and confusing approach that is in use and may be amended.

Quoted 3 lines

there's nothing wrong with checking
error codes if you need to.

If that error code defines the case. Here we have not a such.

The wrong parameter to the function will lead to the same error code which is simply wrong.

Quoted 4 lines

Either way, I checked the original patch. If you really think you need to check for property presence and use default in the case the property isn't found and error out on other errors, add helper functions for the purpose instead of open-coding it all.

You mean adding 20+ helpers (at least 5 for arrays, 5 for single element, and doubled for device_/fwnode_) ?! This sounds like way over verbose approach.

Quoted 6 lines

Quoted 6 lines

Quoted 5 lines

It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

Quoted 5 lines

Quoted 5 lines

I'm against this because we have already a dedicated API to check for property presence, why do we need to have another (confusing!) way of doing the same?

Having a dedicated code may help to debug, but shouldn't be used as a main feature in my opinion.

I will send a next version of this patch touching only the present/bool functions.

Quoted 4 lines · Andy Shevchenko

Quoted 3 lines · Sakari Ailus

Quoted 2 lines · Andy Shevchenko

Quoted 1 line · Sakari Ailus

On Tue, Mar 17, 2026 at 10:08:28PM +0100, Andy Shevchenko wrote:

Quoted 17 lines

Quoted 17 lines

Quoted 16 lines

Quoted 3 lines

Quoted 1 line

+ * In order to check for the property presence, use device_property_present().

Do you really think we should add this clause for each of these functions?

Yes, as Guenter pointed out that this has to be documented clearly.

Quoted 1 line

I don't think it belongs here.

And? What should we do then (taking into account my below comments)?

Quoted 2 lines

The error code list doesn't document what is returned if a property doesn't exist (-EINVAL) and it'd be helpful to add this.

No, this change is exactly against this. Because using an error code that may cover not only that case is at bare minimum fragile and layering violation. APIs that require to know the implementation details are not good APIs.

Quoted 5 lines

Quoted 1 line

I have to say I disagree with that,

And I definitely disagree with tribal knowledge based (implementation details as it's not properly documented and can't, because -EINVAL is overloaded) and confusing approach that is in use and may be amended.

In general it's a good idea to document API functions' return values. It certainly won't add to confusion, will it?

Quoted 13 lines

Quoted 2 lines

there's nothing wrong with checking
error codes if you need to.

If that error code defines the case. Here we have not a such.

The wrong parameter to the function will lead to the same error code which is simply wrong.

Quoted 4 lines

Either way, I checked the original patch. If you really think you need to check for property presence and use default in the case the property isn't found and error out on other errors, add helper functions for the purpose instead of open-coding it all.

Quoted 3 lines

You mean adding 20+ helpers (at least 5 for arrays, 5 for single element, and doubled for device_/fwnode_) ?! This sounds like way over verbose approach.

It's still better than open coding this where differentiating behaviour is desired. You'd probably need a few macros to generate the functions for each type needed.

Quoted 5 lines

Quoted 5 lines

Quoted 5 lines

Quoted 4 lines

It would have been best to have a separate error code for this albeit changing this now might not be that troublesome either: very, very few callers depend on receiving such an error code but there are still many callers.

Quoted 7 lines

Quoted 5 lines

Quoted 5 lines

I'm against this because we have already a dedicated API to check for property presence, why do we need to have another (confusing!) way of doing the same?

Having a dedicated code may help to debug, but shouldn't be used as a main feature in my opinion.

I will send a next version of this patch touching only the present/bool functions.

Sounds good.

I'd also drop this from the patch

+ * This function is the correct way to check that given property is present
+ * in the firmware node description.

as redundant.

Currently it's unclear if one may or may not rely on the error codes returned from the property getters to check for the property presence. Clarify this by mass updating kernel-doc for fwnode_property_*() and device_property_*() where it's applicable.

Reported-by Guenter Roeck <[email protected]>

Closes [email protected]

Signed-off-by Andy Shevchenko <[email protected]>

---
 drivers/base/property.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

drivers/base/property.c +35 -4

index 8d9a34be57fb..bffa0070ab13 100644
@@ -38,6 +38,8 @@ EXPORT_SYMBOL_GPL(__dev_fwnode_const);
  * @propname: Name of the property
  *
  * Check if property @propname is present in the device firmware description.
+ * This function is the correct way to check that given property is present
+ * in the device firmware description.
  *
  * Return: true if property @propname is present. Otherwise, returns false.
  */

@@ -52,6 +54,10 @@ EXPORT_SYMBOL_GPL(device_property_present);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
+ * Check if property @propname is present in the firmware node description.
+ * This function is the correct way to check that given property is present
+ * in the firmware node description.
+ *
  * Return: true if property @propname is present. Otherwise, returns false.
  */
 bool fwnode_property_present(const struct fwnode_handle *fwnode,

@@ -75,9 +81,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
  * @dev: Device whose property is being checked
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the device firmware description.
+ * Use device_property_present() to check for the property presence.
  *
- * Return: true if property @propname is present. Otherwise, returns false.
+ * Return: if property @propname is true or false in the device firmware description.
  */
 bool device_property_read_bool(const struct device *dev, const char *propname)
 {

@@ -90,7 +96,9 @@ EXPORT_SYMBOL_GPL(device_property_read_bool);
  * @fwnode: Firmware node whose property to check
  * @propname: Name of the property
  *
- * Return if property @propname is true or false in the firmware description.
+ * Use fwnode_property_present() to check for the property presence.
+ *
+ * Return: if property @propname is true or false in the firmware node description.
  */
 bool fwnode_property_read_bool(const struct fwnode_handle *fwnode,
                             const char *propname)

@@ -121,6 +129,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_bool);
  * It's recommended to call device_property_count_u8() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -149,6 +159,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
  * It's recommended to call device_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -177,6 +189,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
  * It's recommended to call device_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -205,6 +219,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
  * It's recommended to call device_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -233,6 +249,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
  * It's recommended to call device_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *        number of values available on success if @val is NULL,
  *        %-EINVAL if given arguments are not valid,

@@ -257,6 +275,8 @@ EXPORT_SYMBOL_GPL(device_property_read_string_array);
  * Function reads property @propname from the device firmware description and
  * stores the value into @val if found. The value is checked to be a string.
  *
+ * In order to check for the property presence, use device_property_present().
+ *
  * Return: %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,
  *        %-ENODATA if the property does not have a value,

@@ -324,6 +344,8 @@ static int fwnode_property_read_int_array(const struct fwnode_handle *fwnode,
  * It's recommended to call fwnode_property_count_u8() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -353,6 +375,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);
  * It's recommended to call fwnode_property_count_u16() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -382,6 +406,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);
  * It's recommended to call fwnode_property_count_u32() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -411,6 +437,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);
  * It's recommended to call fwnode_property_count_u64() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values if @val was %NULL,
  *         %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,

@@ -440,6 +468,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);
  * It's recommended to call fwnode_property_string_array_count() instead of calling
  * this function with @val equals %NULL and @nval equals 0.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: number of values read on success if @val is non-NULL,
  *        number of values available on success if @val is NULL,
  *        %-EINVAL if given arguments are not valid,

@@ -476,6 +506,8 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
  * Read property @propname from the given firmware node and store the value into
  * @val if found.  The value is checked to be a string.
  *
+ * In order to check for the property presence, use fwnode_property_present().
+ *
  * Return: %0 if the property was found (success),
  *        %-EINVAL if given arguments are not valid,
  *        %-ENODATA if the property does not have a value,
--

2.50.1