Messages in this thread |  | | | Date | Sun, 29 Mar 2009 17:48:36 +0200 | | From | Jean Delvare <> | | Subject | Class device namespaces |
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Hi Greg,
I am a little confused by the directories created when one registers a class device. When a class device is registered as the children of a real device, a subdirectory by the class name is created, and the class device is created there, effectively granting each class a separate namespace. Example:
/sys/devices/pci0000:00/0000:00:1f.3/i2c-adapter/i2c-0 where 0000:00:1f.3 is the physical device, i2c-adapter the class name and i2c-0 the class device. OTOH, if I create a class device as the children of another class device, the class device is created directly, without a directory between the parent and the child. Example:
/sys/class/i2c-adapter/i2c-0/i2c-0
where the first i2c-0 is an i2c-adapter class device, and the second i2c-0 is an i2c-dev class device. I would have expected:
/sys/class/i2c-adapter/i2c-0/i2c-dev/i2c-0
The current behavior seems inconsistent to me. Is it done so on purpose, or is this accidental? If on purpose, what's the reason?
I am asking because this is causing trouble in practice. We have both i2c-dev and firmware_class which try to create class devices by the same name and this of course collides. While I would blame firmware_class for coming up with an horrible naming scheme (or actually, for not coming up with any naming scheme) it might still be a good idea to prevent such collisions at the driver core level.
Thanks, -- Jean Delvare
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