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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Thu, 20 Apr 2023 16:06:08 +0200
Message-ID: <CAJZ5v0gmDgb+VFwZecbKrbiBejAvODT38Ws=B_wGEGeBHTGR+Q@mail.gmail.com>
Subject: Re: [PATCH] device property: make device_property functions take
 const device *
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Daniel Scally <djrscally@gmail.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Chris Packham <chris.packham@alliedtelesis.co.nz>
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On Wed, Apr 19, 2023 at 6:41 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> device_property functions do not modify the device pointer passed to them.
> The underlying of_device and fwnode_ functions actually already take
> const * arguments. Mark the parameter constant to simplify conversion
> from of_property to device_property functions, and to let the calling code
> use const device pointers where possible.
>
> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Acked-by: Rafael J. Wysocki <rafael@kernel.org>

> ---
> Found by Chris when trying to convert a driver from of_property_ to
> device_property_ functions. I don't really see a reason why the device
> parameter to device_property functions should not be const.
> Please let me know if I am missing sonething.
>
>  drivers/base/property.c  | 16 ++++++++--------
>  include/linux/property.h | 36 ++++++++++++++++++------------------
>  2 files changed, 26 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 083a95791d3b..21d7a5d13e05 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -38,7 +38,7 @@ EXPORT_SYMBOL_GPL(__dev_fwnode_const);
>   *
>   * Check if property @propname is present in the device firmware description.
>   */
> -bool device_property_present(struct device *dev, const char *propname)
> +bool device_property_present(const struct device *dev, const char *propname)
>  {
>         return fwnode_property_present(dev_fwnode(dev), propname);
>  }
> @@ -86,7 +86,7 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
>   *        %-EOVERFLOW if the size of the property is not as expected.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_u8_array(struct device *dev, const char *propname,
> +int device_property_read_u8_array(const struct device *dev, const char *propname,
>                                   u8 *val, size_t nval)
>  {
>         return fwnode_property_read_u8_array(dev_fwnode(dev), propname, val, nval);
> @@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
>   *        %-EOVERFLOW if the size of the property is not as expected.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_u16_array(struct device *dev, const char *propname,
> +int device_property_read_u16_array(const struct device *dev, const char *propname,
>                                    u16 *val, size_t nval)
>  {
>         return fwnode_property_read_u16_array(dev_fwnode(dev), propname, val, nval);
> @@ -142,7 +142,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
>   *        %-EOVERFLOW if the size of the property is not as expected.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_u32_array(struct device *dev, const char *propname,
> +int device_property_read_u32_array(const struct device *dev, const char *propname,
>                                    u32 *val, size_t nval)
>  {
>         return fwnode_property_read_u32_array(dev_fwnode(dev), propname, val, nval);
> @@ -170,7 +170,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
>   *        %-EOVERFLOW if the size of the property is not as expected.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_u64_array(struct device *dev, const char *propname,
> +int device_property_read_u64_array(const struct device *dev, const char *propname,
>                                    u64 *val, size_t nval)
>  {
>         return fwnode_property_read_u64_array(dev_fwnode(dev), propname, val, nval);
> @@ -198,7 +198,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
>   *        %-EOVERFLOW if the size of the property is not as expected.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_string_array(struct device *dev, const char *propname,
> +int device_property_read_string_array(const struct device *dev, const char *propname,
>                                       const char **val, size_t nval)
>  {
>         return fwnode_property_read_string_array(dev_fwnode(dev), propname, val, nval);
> @@ -220,7 +220,7 @@ EXPORT_SYMBOL_GPL(device_property_read_string_array);
>   *        %-EPROTO or %-EILSEQ if the property type is not a string.
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_read_string(struct device *dev, const char *propname,
> +int device_property_read_string(const struct device *dev, const char *propname,
>                                 const char **val)
>  {
>         return fwnode_property_read_string(dev_fwnode(dev), propname, val);
> @@ -242,7 +242,7 @@ EXPORT_SYMBOL_GPL(device_property_read_string);
>   *        %-EPROTO if the property is not an array of strings,
>   *        %-ENXIO if no suitable firmware interface is present.
>   */
> -int device_property_match_string(struct device *dev, const char *propname,
> +int device_property_match_string(const struct device *dev, const char *propname,
>                                  const char *string)
>  {
>         return fwnode_property_match_string(dev_fwnode(dev), propname, string);
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 0a29db15ff34..66fe73ee430d 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -40,20 +40,20 @@ struct fwnode_handle *__dev_fwnode(struct device *dev);
>                  const struct device *: __dev_fwnode_const,     \
>                  struct device *: __dev_fwnode)(dev)
>
> -bool device_property_present(struct device *dev, const char *propname);
> -int device_property_read_u8_array(struct device *dev, const char *propname,
> +bool device_property_present(const struct device *dev, const char *propname);
> +int device_property_read_u8_array(const struct device *dev, const char *propname,
>                                   u8 *val, size_t nval);
> -int device_property_read_u16_array(struct device *dev, const char *propname,
> +int device_property_read_u16_array(const struct device *dev, const char *propname,
>                                    u16 *val, size_t nval);
> -int device_property_read_u32_array(struct device *dev, const char *propname,
> +int device_property_read_u32_array(const struct device *dev, const char *propname,
>                                    u32 *val, size_t nval);
> -int device_property_read_u64_array(struct device *dev, const char *propname,
> +int device_property_read_u64_array(const struct device *dev, const char *propname,
>                                    u64 *val, size_t nval);
> -int device_property_read_string_array(struct device *dev, const char *propname,
> +int device_property_read_string_array(const struct device *dev, const char *propname,
>                                       const char **val, size_t nval);
> -int device_property_read_string(struct device *dev, const char *propname,
> +int device_property_read_string(const struct device *dev, const char *propname,
>                                 const char **val);
> -int device_property_match_string(struct device *dev,
> +int device_property_match_string(const struct device *dev,
>                                  const char *propname, const char *string);
>
>  bool fwnode_property_present(const struct fwnode_handle *fwnode,
> @@ -143,57 +143,57 @@ int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
>
>  unsigned int device_get_child_node_count(const struct device *dev);
>
> -static inline bool device_property_read_bool(struct device *dev,
> +static inline bool device_property_read_bool(const struct device *dev,
>                                              const char *propname)
>  {
>         return device_property_present(dev, propname);
>  }
>
> -static inline int device_property_read_u8(struct device *dev,
> +static inline int device_property_read_u8(const struct device *dev,
>                                           const char *propname, u8 *val)
>  {
>         return device_property_read_u8_array(dev, propname, val, 1);
>  }
>
> -static inline int device_property_read_u16(struct device *dev,
> +static inline int device_property_read_u16(const struct device *dev,
>                                            const char *propname, u16 *val)
>  {
>         return device_property_read_u16_array(dev, propname, val, 1);
>  }
>
> -static inline int device_property_read_u32(struct device *dev,
> +static inline int device_property_read_u32(const struct device *dev,
>                                            const char *propname, u32 *val)
>  {
>         return device_property_read_u32_array(dev, propname, val, 1);
>  }
>
> -static inline int device_property_read_u64(struct device *dev,
> +static inline int device_property_read_u64(const struct device *dev,
>                                            const char *propname, u64 *val)
>  {
>         return device_property_read_u64_array(dev, propname, val, 1);
>  }
>
> -static inline int device_property_count_u8(struct device *dev, const char *propname)
> +static inline int device_property_count_u8(const struct device *dev, const char *propname)
>  {
>         return device_property_read_u8_array(dev, propname, NULL, 0);
>  }
>
> -static inline int device_property_count_u16(struct device *dev, const char *propname)
> +static inline int device_property_count_u16(const struct device *dev, const char *propname)
>  {
>         return device_property_read_u16_array(dev, propname, NULL, 0);
>  }
>
> -static inline int device_property_count_u32(struct device *dev, const char *propname)
> +static inline int device_property_count_u32(const struct device *dev, const char *propname)
>  {
>         return device_property_read_u32_array(dev, propname, NULL, 0);
>  }
>
> -static inline int device_property_count_u64(struct device *dev, const char *propname)
> +static inline int device_property_count_u64(const struct device *dev, const char *propname)
>  {
>         return device_property_read_u64_array(dev, propname, NULL, 0);
>  }
>
> -static inline int device_property_string_array_count(struct device *dev,
> +static inline int device_property_string_array_count(const struct device *dev,
>                                                      const char *propname)
>  {
>         return device_property_read_string_array(dev, propname, NULL, 0);
> --
> 2.39.2
>