03.05.18 23:20, Alan Stern пише: > On Thu, 3 May 2018, Nazar Mokrynskyi wrote: > >> 03.05.18 22:16, Alan Stern пише: >>> On Wed, 2 May 2018, Nazar Mokrynskyi wrote: >>> >>> As far as I know, hubs attached at boot time get initialized and >>> handled in exactly the same way as hubs attached afterward. >>> >>> When a device is connected to a high-speed hub, the hardware in the hub >>> is what determines the device's speed. Not the software in the kernel. >>> The kernel just uses whatever speed the hub says to use. >>> >>> Have you tried a different brand of hub, to see if it makes any >>> difference? >>> >>> Alan Stern >>> >> I had the same issue with different USB hub that was integrated into >> monitor. It had additional power (current hub doesn't), but I don't >> own that monitor anymore (I was using it when reported this issue >> initially). >> >> There is definitely some difference, maybe related to powering USB >> port at early stages of boot process, so that USB hub decides to run >> devices attached to it at slower speed or something tricky like that. > Or maybe it's a noise issue. > >> I've noticed that after boot manager (GRUB) gives control to Linux it >> disconnect USB devices for a short time, but I'm not familiar with >> how and why it happens. > The kernel has to reset all the attached hardware, because it doesn't > know what state the firmware or boot loader left the devices in. > > Anyway, perhaps you can work around this problem with a simple script > that is set to run automatically, shortly after the system boots. The > problem hub is 1-9, right? So the script needs to do this: > > echo 0 >/sys/bus/usb/devices/1-9/bConfigurationValue > echo 1 >/sys/bus/usb/devices/1-9/bConfigurationValue > > That will do a soft reinit of the hub and all the devices attached to > it. Hopefully the reinitialized sound card will run at high speed. > > Alan Stern Interestingly, soft reinit doesn't change anything. Sound card is again initialized at full-speed instead of high-speed. Here is some more information about hub and its devices specifically (including soft reinitialization): https://pastebin.com/DDgnWMQq Sincerely, Nazar Mokrynskyi github.com/nazar-pc -- 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
