Em Mon, 14 Jan 2019 13:10:25 +0800 Kai Hendry <hendry@xxxxxx> escreveu: > Archlinux user here. It doesn't matter whether I'm running LTS kernel 4.19.14-1-lts or 4.20.1.arch1-1, I get these very annoying USB issues with my Magewell XI100DUSB-HDMI. Most of the time it doesn't work. I seemingly have better chances of getting it working after a reboot. > > I don't know if this is a UVC issue or a USB issue on my Gen8 Thinkpad T480s. All I can say for a fact is that plugging this device into my Macbook Pro running MacOS via a USB-C dongle, is more reliable. I've had the same "plug in" issues admittedly on previous Thinkpad hardware and kernel versions. > > Another annoying aspect, is that it also seems to drop USB speeds when hot plugging. I need USB 3 else it won't be able to get 60fps at 1080p. (adding c/c to linux-usb) If the image is not compressed, a 640x480 image with 16 bits per pixel and 30 frames per second eats 60% of the USB 2.0 maximum number of ISOC frames with em28xx driver[1]. [1] The actual value is driver/device specific, as it depends on the maximum frame size. So, I'm pretty sure that you won't be able to get 60fps at 1080p if it doesn't enable USB 3.0 SuperSpeed mode. That's said, it is up to the USB stack to detect the device as an USB 3.0. If this is not working well, it could either be a hardware problem or some issue at the USB host driver. > https://s.natalian.org/2019-01-14/1547438681_2548x1398.png > > It's a crazy ritual with accompanying dance when I get USB3 and my /dev/video2 actually working. > > This is what dmesg looks like when it's flailing. > > [ 71.896534] usb 2-2: Disable of device-initiated U1 failed. > [ 71.900554] usb 2-2: Disable of device-initiated U2 failed. > [ 71.909474] usb 2-2: Set SEL for device-initiated U1 failed. > [ 72.691371] usb 2-2: USB disconnect, device number 6 > [ 73.041273] usb 1-2: new high-speed USB device number 10 using xhci_hcd > [ 73.620177] usb 1-2: New USB device found, idVendor=2935, idProduct=0001, bcdDevice= 0.00 > [ 73.620180] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > [ 73.620182] usb 1-2: Product: XI100DUSB-HDMI > [ 73.620183] usb 1-2: Manufacturer: Magewell > [ 73.620185] usb 1-2: SerialNumber: C021150326019 > [ 76.920993] usb 2-2: Set SEL for device-initiated U2 failed. Everything here happens at USB host driver and USB subsystem. > [ 76.923341] uvcvideo: Found UVC 1.00 device XI100DUSB-HDMI (2935:0001) > [ 76.925324] uvcvideo 1-2:1.0: Entity type for entity Processing 2 was not initialized! > [ 76.925327] uvcvideo 1-2:1.0: Entity type for entity Camera 1 was not initialized! The above is at uvcvideo, and seems OK to my eyes. > [ 76.925413] input: XI100DUSB-HDMI: XI100DUSB-HDMI as /devices/pci0000:00/0000:00:14.0/usb1/1-2/1-2:1.0/input/input25 > [ 76.928710] usbhid 1-2:1.4: couldn't find an input interrupt endpoint This is related to input/evdev probing. Also unrelated to media. > [ 91.516482] usb 1-2: USB disconnect, device number 10 This is also at USB subsystem. Usually, it indicates a bad contact at the USB cable. > Is there any workarounds or ideas to make my capture device less annoying? Thank you in advance, I would try to buy a high quality USB 3.0 cable, and see if things improve. You should remember that a USB 3.0 data transfer will use higher frequency signals, making the cable more susceptible to interference. So, a cable with a good shield can make a difference, specially if you're passing it close to other cables. Thanks, Mauro
