linux-kernel - Re: [PATCH 15/18] i2c: i2c-core-acpi: Add i2c_acpi_dev

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Date:   Mon, 30 Nov 2020 19:11:16 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Daniel Scally <djrscally@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...ica.org, rjw@...ysocki.net,
        lenb@...nel.org, gregkh@...uxfoundation.org,
        mika.westerberg@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
        linus.walleij@...aro.org, bgolaszewski@...libre.com,
        wsa@...nel.org, yong.zhi@...el.com, sakari.ailus@...ux.intel.com,
        bingbu.cao@...el.com, tian.shu.qiu@...el.com, mchehab@...nel.org,
        robert.moore@...el.com, erik.kaneda@...el.com, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        linux@...musvillemoes.dk, kieran.bingham+renesas@...asonboard.com,
        jacopo+renesas@...ndi.org,
        laurent.pinchart+renesas@...asonboard.com,
        jorhand@...ux.microsoft.com, kitakar@...il.com,
        heikki.krogerus@...ux.intel.com
Subject: Re: [PATCH 15/18] i2c: i2c-core-acpi: Add i2c_acpi_dev_name()

Hi Daniel,

Thank you for the patch.

On Mon, Nov 30, 2020 at 01:31:26PM +0000, Daniel Scally wrote:
> Some places in the kernel allow users to map resources to a device
> using device name (for example, gpiod_lookup_table). Currently
> this involves waiting for the i2c_client to have been registered so we
> can use dev_name(&client->dev). Adding this function means that we can
> achieve the same thing without having to wait to the i2c device.
> 
> Signed-off-by: Daniel Scally <djrscally@...il.com>
> ---
> Changes since RFC v3:
> 
> 	- Patch introduced
> 
>  drivers/i2c/i2c-core-acpi.c | 14 ++++++++++++++
>  include/linux/i2c.h         |  5 +++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> index 37c510d9347a..d3a653eac79e 100644
> --- a/drivers/i2c/i2c-core-acpi.c
> +++ b/drivers/i2c/i2c-core-acpi.c
> @@ -497,6 +497,20 @@ struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
>  }
>  EXPORT_SYMBOL_GPL(i2c_acpi_new_device);
>  
> +/**
> + * i2c_acpi_dev_name - Construct i2c device name for devs sourced from ACPI
> + * @adev:     ACPI device to construct the name for
> + *
> + * Prefixes "i2c-" to the ACPI device name, for use in i2c_dev_set_name() and
> + * also anywhere else in the kernel that needs to refer to an i2c device by
> + * name but before they have been instantiated.

The documentation should state that the caller must free the return
value.

> + */
> +char *i2c_acpi_dev_name(struct acpi_device *adev)
> +{
> +	return kasprintf(GFP_KERNEL, "i2c-%s", acpi_dev_name(adev));
> +}
> +EXPORT_SYMBOL_GPL(i2c_acpi_dev_name);
> +
>  #ifdef CONFIG_ACPI_I2C_OPREGION
>  static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
>  		u8 cmd, u8 *data, u8 data_len)
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 56622658b215..ab0e505b2ca6 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -995,6 +995,7 @@ bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
>  u32 i2c_acpi_find_bus_speed(struct device *dev);
>  struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
>  				       struct i2c_board_info *info);
> +char *i2c_acpi_dev_name(struct acpi_device *adev);
>  struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle);
>  #else
>  static inline bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
> @@ -1011,6 +1012,10 @@ static inline struct i2c_client *i2c_acpi_new_device(struct device *dev,
>  {
>  	return ERR_PTR(-ENODEV);
>  }
> +static inline char *i2c_acpi_dev_name(struct acpi_device *adev)
> +{
> +	return NULL;
> +}
>  static inline struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
>  {
>  	return NULL;

-- 
Regards,

Laurent Pinchart