On Wed, 20 Jan 2010, sai pavan wrote:
> Hi All,
>
> We have a usb device which supports multiple usb functions. We would
> like to support dynamic configuration based on user input. i.e We have
> a array of product ids and each product id consists of different usb
> functions. for example
>
> product id A : mass storage
>
> product id B: CDC-ECM
>
> product id C: mass storage + CDC-ACM
>
> We can compile composite driver as a DLKM (g_myusb.ko) which takes
> product id as a module parameter. Based on product id we can prepare
> configuration and the corresponding functions only will be active i.e
> remaining function drivers bind will not be called. Every time user
> wants to switch to a different composition, we reload the module with
> a different product id as module parameter.
>
> We want to extend the same functionality for statically compiled
> composite driver as well. We can register sysfs handler function to
> receive a product id module parameter. The default product id can be
> passed via kernel command line. If nothing is passed, usb device will
> not be enumerated till product id is passed from user.
>
> sysfs_function(u16 pid)
> {
> composite_driver_unregister(&previous);
> composite_driver_register(&new);
> }
>
> But gadget function driver bind and unbind methods are marked as
> __init and __exit. Is it okay to remove these macros to support this
> feature? Is there a better approach to achieve this functionality? Any
> pointers on how different usb devices (mostly phones) support this
> functionality?
Since you want to support dynamic configuration, why not use multiple
USB configurations?
Alan Stern
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