Petr, On 02/03/17 06:57, Petr Cvek wrote: > Dne 2.3.2017 v 00:22 Laurent Pinchart napsal(a): >> Hi Roger, >> >> On Wednesday 01 Mar 2017 17:09:51 Roger Quadros wrote: >>> Hi, >>> >>> I'm no longer able to use g_webcam with uvc-gadget [1] since v4.9. Logs at >>> the end. It looks like we're goofing up on the control endpoint. >>> >>> If I revert the following commit everything works fine. >>> commit 4fbac5206afd01b717d4bdc58793d471f3391b4b >>> Author: Petr Cvek <petr.cvek@xxxxxx> >>> Date: Wed Aug 17 12:36:57 2016 +0200 >>> >>> usb: gadget: uvc: Add missing call for additional setup data >>> >>> Am I missing something on uvc-gadget side or is the commit really bad? >>> From what I understand, uvc-gadget is responsible for sending response to >>> UVC class specific requests on control endpoint in uvc_send_response() >>> in uvc_v4l2.c. >>> >>> So the reported commit is sending a duplicate response with probably >>> improper data. >> >> Yes, this looks very dubious to me. I think it should be reverted. My >> apologies for not having caught the patch during review. > > Hi, > > Now I've watched all codepaths again and yeah it is probably wrong patch, sorry. > > But if the code path is really: > > uvc_function_setup() -> userspace setup -> ioctl UVCIOC_SEND_RESPONSE -> uvc_send_response() -> usb_ep_queue() -> uvc_function_ep0_complete() -> userspace data > > it seems the USB timeouts with my hardware (PXA27x UDC) but with my patch it gets response immediately. > I hope you were running uvc-gadget application on the PXA27x. Just sending a response is not sufficient. It must send a response with proper data. f_uvc itself doesn't know how to handle UVC class specific requests and has to depend on the user space application to populate the data in the response. -- cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
