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

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Message-ID: <30414f42-fdf4-c4f3-6a41-3da9f105a7a1@gmail.com>
Date:   Wed, 2 Dec 2020 22:44:36 +0000
From:   Dan Scally <djrscally@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.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()

On 30/11/2020 17:11, Laurent Pinchart wrote:
> 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.

Updated to include that - thanks

>> + */
>> +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;
>