Hi Joseph, Hi Bin, I am currently investigating a bug with the BeagleBoneBlack (which also uses the AM335x) and a Logitech Webcam, which might be connected. I am using a Logitech C270 and if I set the format to YUYV and the framesize to 544x288 or larger (including specifically 640x480), any ioctl VIDIOC_DQBUF will hang indefinetely. This might be the underlying source of the timeout Joseph encountered. Joseph, have you tried setting the camera to the lowest resolution it can go? If low resolutions work, but higher ones, like 640x480 don't, we might be chasing the same problem. If not, I will look into my problem separately and open a new thread. Bin, my case happened using ISOC transfers, but my preliminary investigation has shown lots of ISOC traffic flowing, apparently successfuly from the camera to the BBB, which makes me suspect a problem closer to the v4l2/musb boundary, but I'm still reading into the code. If you would like to investigate that further, the C270 is rather affordable, but I will gladly provide any details, usbmon captures etc. that you require. Cheers, Joel Pepper On 19.10.2018 20:06, Josep M. Mirats Tur wrote: > Hi Bin, > >> Do you know what is the usb throughput required in your test case? for >> example image format, resolution, frame rate? Is the usb data transfer >> bulk or isoch? > Yes, the image format is 640 x 480 > The camera can run up to 30fps, although I do not need it and set up it to 5 > The Usb data transfer is "bulk" > > Regards > Josep M. > > On Fri, Oct 19, 2018 at 8:01 PM Bin Liu <b-liu@xxxxxx> wrote: >> On Fri, Oct 19, 2018 at 07:48:20PM +0200, Josep M. Mirats Tur wrote: >>> Hi, >>> >>> Yes, this would be the link: >>> http://shop-orbbec3d-com.3dcartstores.com/Astra-Mini_p_40.html >> Okay, It is about $160, a bit more than my bugdet... >> >>> In the meanwhile I'll check my application with other board. >>> >>> Do you think there might be a problem with the processor frequency? >>> I've also crossing e-mails with ORBBEC engineers, and their only >>> answer has been to suggest using an ARM processor capable of 1.8GHz >>> Beagle is capable of 1GHz >>> But I can not see why is this so important as long as USB is well >>> synchronized and interrupts and driver work well. (Actually I'm not >>> familiar with ARM USB system, is just intuition) >> I guess the cpu clock requirement is only to ensure the whole system is >> capable to process the usb packets, depending on the image resolution, >> fps, and any other data processing. But lower cpu clock shouldn't cause >> such problem that the usb controller generates rx interrupt but fifo has >> no usb packet. If ARM cannot keep up, which doesn't send IN requests on >> time, the camera should just drop data. >> >> Do you know what is the usb throughput required in your test case? for >> example image format, resolution, frame rate? Is the usb data transfer >> bulk or isoch? >> >> Regards, >> -Bin.
