The fwnode_irq_get() and the fwnode_irq_get_byname() return 0 upon
device-tree IRQ mapping failure. This is contradicting the
fwnode_irq_get_byname() function documentation and can potentially be a
source of errors like:

int probe(...) {
	...

	irq = fwnode_irq_get_byname();
	if (irq <= 0)
		return irq;

	...
}

Here we do correctly check the return value from fwnode_irq_get_byname()
but the driver probe will now return success. (There was already one
such user in-tree).

Change the fwnode_irq_get_byname() to work as documented and make also the
fwnode_irq_get() follow same common convention returning a negative errno
upon failure.

Fixes: ca0acb511c21 ("device property: Add fwnode_irq_get_byname")
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
I dropped the existing reviewed-by tags because change to
fwnode_irq_get() was added.

Revision history:
v3 => v4:
 - Change also the fwnode_irq_get()
---
 drivers/base/property.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index f6117ec9805c..8c40abed7852 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -987,12 +987,18 @@ EXPORT_SYMBOL(fwnode_iomap);
  * @fwnode:	Pointer to the firmware node
  * @index:	Zero-based index of the IRQ
  *
- * Return: Linux IRQ number on success. Other values are determined
- * according to acpi_irq_get() or of_irq_get() operation.
+ * Return: Linux IRQ number on success. Negative errno on failure.
  */
 int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index)
 {
-	return fwnode_call_int_op(fwnode, irq_get, index);
+	int ret;
+
+	ret = fwnode_call_int_op(fwnode, irq_get, index);
+	/* We treat mapping errors as invalid case */
+	if (ret == 0)
+		return -EINVAL;
+
+	return ret;
 }
 EXPORT_SYMBOL(fwnode_irq_get);
 
-- 
2.40.1


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

Fri, May 19, 2023 at 02:00:54PM +0300, Matti Vaittinen kirjoitti:
> The fwnode_irq_get() and the fwnode_irq_get_byname() return 0 upon
> device-tree IRQ mapping failure. This is contradicting the
> fwnode_irq_get_byname() function documentation and can potentially be a
> source of errors like:
> 
> int probe(...) {
> 	...
> 
> 	irq = fwnode_irq_get_byname();
> 	if (irq <= 0)
> 		return irq;
> 
> 	...
> }
> 
> Here we do correctly check the return value from fwnode_irq_get_byname()
> but the driver probe will now return success. (There was already one
> such user in-tree).
> 
> Change the fwnode_irq_get_byname() to work as documented and make also the
> fwnode_irq_get() follow same common convention returning a negative errno
> upon failure.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Fixes: ca0acb511c21 ("device property: Add fwnode_irq_get_byname")
> Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Suggested-by: Jonathan Cameron <jic23@kernel.org>
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---
> I dropped the existing reviewed-by tags because change to
> fwnode_irq_get() was added.
> 
> Revision history:
> v3 => v4:
>  - Change also the fwnode_irq_get()
> ---
>  drivers/base/property.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index f6117ec9805c..8c40abed7852 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -987,12 +987,18 @@ EXPORT_SYMBOL(fwnode_iomap);
>   * @fwnode:	Pointer to the firmware node
>   * @index:	Zero-based index of the IRQ
>   *
> - * Return: Linux IRQ number on success. Other values are determined
> - * according to acpi_irq_get() or of_irq_get() operation.
> + * Return: Linux IRQ number on success. Negative errno on failure.
>   */
>  int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index)
>  {
> -	return fwnode_call_int_op(fwnode, irq_get, index);
> +	int ret;
> +
> +	ret = fwnode_call_int_op(fwnode, irq_get, index);
> +	/* We treat mapping errors as invalid case */
> +	if (ret == 0)
> +		return -EINVAL;

Not sure if this is the best choice, perhaps -EEXIST or -ENOENT might be
better, but it's just a spoken up thought.

> +	return ret;
>  }
>  EXPORT_SYMBOL(fwnode_irq_get);

-- 
With Best Regards,
Andy Shevchenko