On Sun, Nov 05, 2023 at 04:33:00PM +0100, Fabian Melzow wrote: > Am Sun, 5 Nov 2023 09:56:06 -0500 > schrieb Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > > > On Sun, Nov 05, 2023 at 02:30:51PM +0100, Fabian Melzow wrote: > > > Am Sun, 5 Nov 2023 14:11:02 +0100 > > > schrieb Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>: > > > > > > > On Sun, Nov 05, 2023 at 01:49:09PM +0100, Fabian Melzow wrote: > > > > > Am Sun, 5 Nov 2023 13:20:38 +0100 > > > > > schrieb Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>: > > > > > > > > > > > On Sun, Nov 05, 2023 at 01:02:15PM +0100, Fabian Melzow > > > > > > wrote: > > > > > > > These devices should report 5 Gbps for USB 3.0 in the Binary > > > > > > > Object Store Descriptor, but don't do so. > > > > > > > > > > > > Why do you think these should report 5 Gbps? If the device > > > > > > descriptor does not show it, there's nothing that we can do > > > > > > about it in the operating system, sorry. > > > > > > > > > > Thanks. I don't look at the USB specification for USB >2.0, > > > > > which was long times ago and then only for a user space program > > > > > and thought that it at least theoretically could be possible to > > > > > set the device speed at some kind of initialization. > > > > > > > > There might be some vendor-specific way of doing this, and then > > > > the device resets itself, but other than that, no, descriptors > > > > are a static description of the device's capabilities. > > > > > > When this static description is also used by the host controller to > > > set the device speed, then these WLAN devices are limited to 480 > > > Mbps. If > > > > The speed is not set by the host controller; it is set by the device. > > > > If the device is capable of running at a higher speed than 480 Mbps > > then it should do so. Have you checked the actual connection speed, > > as reported in the "speed" file in the device's sysfs directory or in > > the output from "lsusb -t"? > > $ lsusb -t (only relevant output) > /: Bus 001.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/14p, 480M > |__ Port 004: Dev 003, If 0, Class=Vendor Specific Class, Driver=rtw_8822bu, 480M > > > > How do you know that the device's USB hardware supports more than 480 > > Mbps? And even if the hardware does, maybe the firmware doesn't. > > > > (Note: Just because the device's WLAN interface can run at 780 Mbps, > > it does not follow that the USB interface can run that fast.) > > These USB WLAN sticks are sold as "USB 3.0", and also have a blue > USB-3.0-A-plug. I don't really know the speed, but 480 Mbps is reported > by "lsusb -t" or in the descriptor. I did not open these devices, but > have assumed that they only use a single chip to handle everything, > WLAN and USB. Have you tried plugging the device into a system running a different OS (Windows or MacOS-X)? Or even a different Linux system? Alan Stern
