Hi Vitaly,
On Wed, Dec 1, 2010 at 12:41 AM, Vitaly Kuzmichev vkuzmichev@mvista.com wrote:
Hi Lei,
Lei Wen wrote:
[...]
For current ether.c state, there is no usb_gadget_unregister_driver in it. Even it has, we still need usb_gadget_register_driver call in each eth_init().
Yes, if we do 'unregister' we should do 'register' somewhere before. If we do 'register' we should do 'unregister' somewhere after. This is the symmetry such like in dynamic data allocation (like malloc/free), and we should comply it. The reason why there is no 'usb_gadget_unregister_driver' in the Ether driver yet is that there is no symmetrical function for 'usb_eth_initialize' because there is no way to remove a network device from the U-Boot environment.
What we need to do is not trying to remove the network device, but to register another gadget when we want to switch from tftp to fastboot, and make UDC take a different protocol to communicate with host.
I have not asked you to remove network device, I have talked about the reason for the following:
For current ether.c state, there is no usb_gadget_unregister_driver in it.
[...]
Right, if at the same time certainly need to return error.
So your code that expects successful register will make Ether gadget broken...
Don't understand here, why the Ether gadget would be broken?
Because UDC driver does not allow to register more than 1 gadget driver in the same time. It just returns EBUSY. Even if the first gadget driver is idle (when Ether gadget driver is registered but tftp command is not issued). This is done to protect against memory leaks. Just checkout cdc-at91 branch in u-boot-usb.git for example of UDC driver (drivers/usb/gadget/at91_udc.c). Or look at any UDC driver in linux kernel.
I add unregister function in eth_halt, then the udc driver could do the proper memory free to prevent the memory leak.
[...]
This means that if you want 2 gadgets you need to register each one right before transferring data and unregister right after the data was transferred. By doing gadget unregister you will free allocated resources (such as USB endpoints and USB requests) in UDC and Ether drivers properly. Otherwise you will have memory leaks.
Sure, so we comes into a conclusion that add register call in the eth_init and unregister call in eth_halt? In unregister call, the UDC driver should free the ep as you said.
Yes, it will free by 'eth_unbind' called from 'usb_gadget_unregister_driver'.
Note that 'usb_gadget_register_driver' should be removed from 'usb_eth_initialize' and dev->gadget checking should be added in eth_halt.
Ack this idea. Apply to the next patch.
Best regards, Lei