On 07/07/2012 06:09 PM, Oleksij Rempel wrote: > On 07.07.2012 11:20, Eric Ding wrote: >> On 07/06/2012 11:47 PM, Alan Stern wrote: >>> On Fri, 6 Jul 2012, Alan Cox wrote: >>> >>>>> Yes, but we still need to know the reason why. Neither Rafael nor I >>>>> has been able to figure out why that commit messed things up. >>>> >>>> Was the driver doing any dynamic autosuspend at all until that point ? >>> >>> I don't know... but whatever it was doing before the commit, it should >>> be doing the same thing afterward. >> >> I thought that getting some comparative usbmon logs might help, but I'm >> not equipped to parse them. To generate these logs, I ran guvcview once >> after plugging in the webcam, then did the following upon quiting >> guvcview: start listening via usbmon, sleep for four seconds, start >> guvcview again and stop listening via usbmon after four seconds. >> >> I did this both at commit e1620d5 (the commit which triggered this >> issue) and once at commit 9975961 (one commit prior). Going through >> these motions also confirmed that the problem is readily reproducible >> the second time I start guvcview at e1620d5, but not at 9975961. I've >> attached both logs in case they're helpful. > > In both logs you send the cam start to stream video. Major difference is > that, after suspend/resume it need more time (about 10 seconds) to start > stream. Is it correct? My tests didn't continue a full 10 seconds after I restarted the webcam, so I'm not sure I follow your question. In the second case (with e1620d5), the camera never returns a "normal" video image -- instead, it gets a garbled video image of horizontal stripes, which change with what the camera lens is seeing, but are obviously not the correct image. The stream does take longer to come up on the second time than the first, though, during which I see the following error message in guvcview 1-3 times: Could not grab image (select timeout): Resource temporarily unavailable Sorry if I'm not answering your question helpfully! Eric -- 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
