Dear All, I may have found a problem with 'deferred configuration' mode in gadgetfs. Or, more likely, I have misunderstood something or found an error that you already know about...
Normally, activate_ep_files() creates inodes for the per-endpoint files with f_op set to ep_config_operations. The endpoint descriptors are then written to these files and are processed by ep_config(). This will call usb_ep_enable() and if all is OK it will change f_op to ep_io_operations, so endpoint reads and writes call ep_read() and ep_write respectively, transfering real data. However, endpoint descriptors can be written before the device is connected, in which case the speed of the connection is not known; to cope with this the code in ep_config() can postpone actual configuration. It does this by setting the endpoint state to STATE_EP_DEFER_ENABLE. Subsequently, endpoints in this state are checked for in gadgetfs_setup(), which is called in response to a CONNECT message, and usb_ep_enable() is called from there. However, in this case, f_op is not changed over to ep_io_operations, and endpoint reads and writes do not go to ep_read() and ep_write(). I can see two possibilities for how this should work: 1. f_op could be changed over in ep_config() even in the deferred case. This would happen if value equalled 0 in the deferred case; currently as far as I can see it equals len. I am experimenting with this change, and my test program seems to get a bit further than it used to. 2. f_op could be changed over in gadgetfs_setup(), immediately after the call to usb_ep_enable() there. I am unsure about what should happen to the endpoint configurations during DISCONNECT/CONNECT, especially if the speed changes. I worry about this particularly as I always see CONNECT/DISCONNECT/CONNECT when my test program starts - is this normal??? Any thoughts anyone? Cheers, Phil. (You are welcome to CC me in any replies) ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
