linux-kernel - Re: [PATCH 1/2] usb: typec: mux: Use device type instead of device name for matching

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Date:   Mon, 31 May 2021 10:09:19 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Li Jun <jun.li@....com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] usb: typec: mux: Use device type instead of device
 name for matching

Hi,

On 5/31/21 9:30 AM, Heikki Krogerus wrote:
> On Wed, May 26, 2021 at 06:35:47PM +0300, Heikki Krogerus wrote:
>> Both the USB Type-C switch and mux have already a device
>> type defined for them. We can use those types instead of the
>> device name to differentiate the two.
> 
> This should still be OK, right?

I believe so and a dev_type check also seems more robust then
a name-suffix check.

Regards,

Hans


> 
>> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
>> ---
>>  drivers/usb/typec/mux.c | 26 ++++++++++----------------
>>  drivers/usb/typec/mux.h |  6 ++++++
>>  2 files changed, 16 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
>> index 8514bec7e1b89..e40a555724fb6 100644
>> --- a/drivers/usb/typec/mux.c
>> +++ b/drivers/usb/typec/mux.c
>> @@ -17,21 +17,12 @@
>>  #include "class.h"
>>  #include "mux.h"
>>  
>> -static bool dev_name_ends_with(struct device *dev, const char *suffix)
>> -{
>> -	const char *name = dev_name(dev);
>> -	const int name_len = strlen(name);
>> -	const int suffix_len = strlen(suffix);
>> -
>> -	if (suffix_len > name_len)
>> -		return false;
>> -
>> -	return strcmp(name + (name_len - suffix_len), suffix) == 0;
>> -}
>> -
>>  static int switch_fwnode_match(struct device *dev, const void *fwnode)
>>  {
>> -	return dev_fwnode(dev) == fwnode && dev_name_ends_with(dev, "-switch");
>> +	if (!is_typec_switch(dev))
>> +		return 0;
>> +
>> +	return dev_fwnode(dev) == fwnode;
>>  }
>>  
>>  static void *typec_switch_match(struct fwnode_handle *fwnode, const char *id,
>> @@ -90,7 +81,7 @@ static void typec_switch_release(struct device *dev)
>>  	kfree(to_typec_switch(dev));
>>  }
>>  
>> -static const struct device_type typec_switch_dev_type = {
>> +const struct device_type typec_switch_dev_type = {
>>  	.name = "orientation_switch",
>>  	.release = typec_switch_release,
>>  };
>> @@ -180,7 +171,10 @@ EXPORT_SYMBOL_GPL(typec_switch_get_drvdata);
>>  
>>  static int mux_fwnode_match(struct device *dev, const void *fwnode)
>>  {
>> -	return dev_fwnode(dev) == fwnode && dev_name_ends_with(dev, "-mux");
>> +	if (!is_typec_mux(dev))
>> +		return 0;
>> +
>> +	return dev_fwnode(dev) == fwnode;
>>  }
>>  
>>  static void *typec_mux_match(struct fwnode_handle *fwnode, const char *id,
>> @@ -295,7 +289,7 @@ static void typec_mux_release(struct device *dev)
>>  	kfree(to_typec_mux(dev));
>>  }
>>  
>> -static const struct device_type typec_mux_dev_type = {
>> +const struct device_type typec_mux_dev_type = {
>>  	.name = "mode_switch",
>>  	.release = typec_mux_release,
>>  };
>> diff --git a/drivers/usb/typec/mux.h b/drivers/usb/typec/mux.h
>> index 4fd9426ee44f6..b1d6e837cb747 100644
>> --- a/drivers/usb/typec/mux.h
>> +++ b/drivers/usb/typec/mux.h
>> @@ -18,4 +18,10 @@ struct typec_mux {
>>  #define to_typec_switch(_dev_) container_of(_dev_, struct typec_switch, dev)
>>  #define to_typec_mux(_dev_) container_of(_dev_, struct typec_mux, dev)
>>  
>> +extern const struct device_type typec_switch_dev_type;
>> +extern const struct device_type typec_mux_dev_type;
>> +
>> +#define is_typec_switch(dev) ((dev)->type == &typec_switch_dev_type)
>> +#define is_typec_mux(dev) ((dev)->type == &typec_mux_dev_type)
>> +
>>  #endif /* __USB_TYPEC_MUX__ */
>> -- 
>> 2.30.2
>