0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Hello,

I have three USB "3.0" WLAN sticks (https://i.imgur.com/zSg5s0d.jpg)
which are all based on the Realtek RTW8822BU (<=780 Mbps with IEEE
802.11ac) and use the same vendor and product ID 0bda:b812 and have the
exact same output of "lsusb -vd 0bda:b812".

These devices should report 5 Gbps for USB 3.0 in the Binary Object
Store Descriptor, but don't do so.

Maybe it is possible to add a software fix for this hardware
problem, so I report it here.

Output of lsusb from usbutils 017 on x86_64 with kernel 6.6.0:

Bus 001 Device 003: ID 0bda:b812 Realtek Semiconductor Corp. RTL88x2bu [AC1200 Techkey]
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.10
  bDeviceClass            0 [unknown]
  bDeviceSubClass         0 [unknown]
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x0bda Realtek Semiconductor Corp.
  idProduct          0xb812 RTL88x2bu [AC1200 Techkey]
  bcdDevice            2.10
  iManufacturer           1 Realtek
  iProduct                2 USB3.0 802.11ac 1200M Adapter
  iSerial                 3 123456
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0035
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           5
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              2 USB3.0 802.11ac 1200M Adapter
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x05  EP 5 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x87  EP 7 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               3
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x08  EP 8 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Binary Object Store Descriptor:
  bLength                 5
  bDescriptorType        15
  wTotalLength       0x0016
  bNumDeviceCaps          2
  USB 2.0 Extension Device Capability:
    bLength                 7
    bDescriptorType        16
    bDevCapabilityType      2
    bmAttributes   0x00000002
      HIRD Link Power Management (LPM) Supported
  SuperSpeed USB Device Capability:
    bLength                10
    bDescriptorType        16
    bDevCapabilityType      3
    bmAttributes         0x00
    wSpeedsSupported   0x0006
      Device can operate at Full Speed (12Mbps)
      Device can operate at High Speed (480Mbps)
    bFunctionalitySupport   1
      Lowest fully-functional device speed is Full Speed (12Mbps)
    bU1DevExitLat          10 micro seconds
    bU2DevExitLat        1023 micro seconds
Device Status:     0x0000
  (Bus Powered)

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Greg KH]

On Sun, Nov 05, 2023 at 01:02:15PM +0100, Fabian Melzow wrote:
> Hello,
> 
> I have three USB "3.0" WLAN sticks (https://i.imgur.com/zSg5s0d.jpg)
> which are all based on the Realtek RTW8822BU (<=780 Mbps with IEEE
> 802.11ac) and use the same vendor and product ID 0bda:b812 and have the
> exact same output of "lsusb -vd 0bda:b812".
> 
> 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.

> Maybe it is possible to add a software fix for this hardware
> problem, so I report it here.

What exactly is the hardware problem?  What is not working "properly"
for them?

thanks,

greg k-h

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Am Sun, 5 Nov 2023 13:20:38 +0100
schrieb Greg KH <gregkh@linuxfoundation.org>:

> 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.

> > Maybe it is possible to add a software fix for this hardware
> > problem, so I report it here.  
> 
> What exactly is the hardware problem?  What is not working "properly"
> for them?

All 0bda:b812 USB-WLAN-devices seems to only operate at 480 Mbps,
but have a WLAN-chip which supports 780 Mbps at maximum.

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Greg KH]

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@linuxfoundation.org>:
> 
> > 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.

> > > Maybe it is possible to add a software fix for this hardware
> > > problem, so I report it here.  
> > 
> > What exactly is the hardware problem?  What is not working "properly"
> > for them?
> 
> All 0bda:b812 USB-WLAN-devices seems to only operate at 480 Mbps,
> but have a WLAN-chip which supports 780 Mbps at maximum.

Are you sure that those devices really can run at 480 Mbps?  Perhaps the
chip can support higher, but the firmware on the device, and the other
stuff in the device does not?

thanks,

greg k-h

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Am Sun, 5 Nov 2023 14:11:02 +0100
schrieb Greg KH <gregkh@linuxfoundation.org>:

> 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@linuxfoundation.org>:
> >   
> > > 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
these descriptor are more a information for programmers, even if some
descriptors are uses to configure the device, but the hardware supports
more then 480 Mbps, as which in this case, then these devices are not
limited, but provide wrong information.

> > > What exactly is the hardware problem?  What is not working
> > > "properly" for them?  
> > 
> > All 0bda:b812 USB-WLAN-devices seems to only operate at 480 Mbps,
> > but have a WLAN-chip which supports 780 Mbps at maximum.  
> 
> Are you sure that those devices really can run at 480 Mbps?  Perhaps
> the chip can support higher, but the firmware on the device, and the
> other stuff in the device does not?

The used WLAN chipset should support more then 480 Mbps in hardware,
but I don't known whether the host controller limits the speed based on
the wrong descriptor of the device.

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Alan Stern]

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@linuxfoundation.org>:
> 
> > 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@linuxfoundation.org>:
> > >   
> > > > 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"?

> these descriptor are more a information for programmers, even if some
> descriptors are uses to configure the device, but the hardware supports
> more then 480 Mbps, as which in this case, then these devices are not
> limited, but provide wrong information.

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.)

> > > > What exactly is the hardware problem?  What is not working
> > > > "properly" for them?  
> > > 
> > > All 0bda:b812 USB-WLAN-devices seems to only operate at 480 Mbps,
> > > but have a WLAN-chip which supports 780 Mbps at maximum.  
> > 
> > Are you sure that those devices really can run at 480 Mbps?  Perhaps
> > the chip can support higher, but the firmware on the device, and the
> > other stuff in the device does not?
> 
> The used WLAN chipset should support more then 480 Mbps in hardware,
> but I don't known whether the host controller limits the speed based on
> the wrong descriptor of the device.

The speed is not determined by the device's descriptors; it is 
negotiated at the hardware level between the device and the upstream hub 
when the USB port is reset, which happens shortly after the device is 
plugged in, as part of initialization.

Another thing to watch out for: Even a 10-Gbps-capable device will be 
forced to run at a measly 480 Mbps if it is connected via a USB-2 cable 
rather than a USB-3 cable.

Alan Stern

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Am Sun, 5 Nov 2023 09:56:06 -0500
schrieb Alan Stern <stern@rowland.harvard.edu>:

> 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@linuxfoundation.org>:
> >   
> > > 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@linuxfoundation.org>:
> > > >     
> > > > > 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.

> > > > > What exactly is the hardware problem?  What is not working
> > > > > "properly" for them?    
> > > > 
> > > > All 0bda:b812 USB-WLAN-devices seems to only operate at 480
> > > > Mbps, but have a WLAN-chip which supports 780 Mbps at maximum.
> > > >   
> > > 
> > > Are you sure that those devices really can run at 480 Mbps?
> > > Perhaps the chip can support higher, but the firmware on the
> > > device, and the other stuff in the device does not?  
> > 
> > The used WLAN chipset should support more then 480 Mbps in hardware,
> > but I don't known whether the host controller limits the speed
> > based on the wrong descriptor of the device.  
> 
> The speed is not determined by the device's descriptors; it is 
> negotiated at the hardware level between the device and the upstream
> hub when the USB port is reset, which happens shortly after the
> device is plugged in, as part of initialization.
> 
> Another thing to watch out for: Even a 10-Gbps-capable device will be 
> forced to run at a measly 480 Mbps if it is connected via a USB-2
> cable rather than a USB-3 cable.

The above lsusb-output, is from plugging the stick direct into a
10 Gbps-USB 3.1-A-port, with it's A-plug in the case.

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Alan Stern]

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@rowland.harvard.edu>:
> 
> > 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@linuxfoundation.org>:
> > >   
> > > > 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@linuxfoundation.org>:
> > > > >     
> > > > > > 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

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Am Sun, 5 Nov 2023 14:16:18 -0500
schrieb Alan Stern <stern@rowland.harvard.edu>:

> 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@rowland.harvard.edu>:

> > > 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?

Yes, I also made a short test with the lsusb of an old Debian 11
Live-DVD. I got these devices for testing from the Amazon Vine program
and after the third Monday-Hardware WLAN-device with the same problem I
thought I should report this problem, to maybe help real users.

(Forgot to send the mail also to this list.)

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Alan Stern]

On Sun, Nov 05, 2023 at 09:06:16PM +0100, Fabian Melzow wrote:
> Am Sun, 5 Nov 2023 14:16:18 -0500
> schrieb Alan Stern <stern@rowland.harvard.edu>:
> 
> > Have you tried plugging the device into a system running a different
> > OS (Windows or MacOS-X)?  Or even a different Linux system?
> 
> Yes, I also made a short test with the lsusb of an old Debian 11
> Live-DVD. I got these devices for testing from the Amazon Vine program
> and after the third Monday-Hardware WLAN-device with the same problem I
> thought I should report this problem, to maybe help real users.

A test with Windows might be more informative, if you can manage to do 
one.  Perhaps the Windows driver knows how to configure the device to 
run at higher speed.

Also, curiously enough, when I did a web search for reports of problems 
with this chip, the vast majority of messages were about it not working 
with Linux at all because Debian/Ubuntu did not include sufficiently 
up-to-date drivers.  People had to download driver source code from a 
github project and build and install it for themselves in order to get 
the device to function.  They didn't mention what speed it used on the 
USB bus.

Alan Stern

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Fabian Melzow]

Am Sun, 5 Nov 2023 21:10:47 -0500
schrieb Alan Stern <stern@rowland.harvard.edu>:

> On Sun, Nov 05, 2023 at 09:06:16PM +0100, Fabian Melzow wrote:
> > Am Sun, 5 Nov 2023 14:16:18 -0500
> > schrieb Alan Stern <stern@rowland.harvard.edu>:
> >   
> > > Have you tried plugging the device into a system running a
> > > different OS (Windows or MacOS-X)?  Or even a different Linux
> > > system?  
> > 
> > Yes, I also made a short test with the lsusb of an old Debian 11
> > Live-DVD. I got these devices for testing from the Amazon Vine
> > program and after the third Monday-Hardware WLAN-device with the
> > same problem I thought I should report this problem, to maybe help
> > real users.  
> 
> A test with Windows might be more informative, if you can manage to
> do one.  Perhaps the Windows driver knows how to configure the device
> to run at higher speed.
>
> Also, curiously enough, when I did a web search for reports of
> problems with this chip, the vast majority of messages were about it
> not working with Linux at all because Debian/Ubuntu did not include
> sufficiently up-to-date drivers.  People had to download driver
> source code from a github project and build and install it for
> themselves in order to get the device to function.  They didn't
> mention what speed it used on the USB bus.

The Linux rtw88 driver is maintained by Realtek and, if my searching is
right, first appeared in Linux 5.18, so it's a newer one. I could
trigger an Oops, which I also reported yesterday. According to
the Debian backport https://github.com/lwfinger/rtw88 some versions of
the chipset are still unsupported. 

The rwt8822bu driver has also a non-USB version rwt8822b, so the chip
for the USB support can also be separate from the main chip, but until
now don't want to destroy one of the plastic cases.

Fabian Melzow

Re: 0bda:b812 USB "3.0" WLAN devices only report a maximum of 480 Mbps

[Alan Stern]

On Mon, Nov 06, 2023 at 08:00:24AM +0100, Fabian Melzow wrote:
> Am Sun, 5 Nov 2023 21:10:47 -0500
> schrieb Alan Stern <stern@rowland.harvard.edu>:
> 
> > On Sun, Nov 05, 2023 at 09:06:16PM +0100, Fabian Melzow wrote:
> > > Am Sun, 5 Nov 2023 14:16:18 -0500
> > > schrieb Alan Stern <stern@rowland.harvard.edu>:
> > >   
> > > > Have you tried plugging the device into a system running a
> > > > different OS (Windows or MacOS-X)?  Or even a different Linux
> > > > system?  
> > > 
> > > Yes, I also made a short test with the lsusb of an old Debian 11
> > > Live-DVD. I got these devices for testing from the Amazon Vine
> > > program and after the third Monday-Hardware WLAN-device with the
> > > same problem I thought I should report this problem, to maybe help
> > > real users.  
> > 
> > A test with Windows might be more informative, if you can manage to
> > do one.  Perhaps the Windows driver knows how to configure the device
> > to run at higher speed.
> >
> > Also, curiously enough, when I did a web search for reports of
> > problems with this chip, the vast majority of messages were about it
> > not working with Linux at all because Debian/Ubuntu did not include
> > sufficiently up-to-date drivers.  People had to download driver
> > source code from a github project and build and install it for
> > themselves in order to get the device to function.  They didn't
> > mention what speed it used on the USB bus.
> 
> The Linux rtw88 driver is maintained by Realtek and, if my searching is
> right, first appeared in Linux 5.18, so it's a newer one. I could
> trigger an Oops, which I also reported yesterday. According to
> the Debian backport https://github.com/lwfinger/rtw88 some versions of
> the chipset are still unsupported. 
> 
> The rwt8822bu driver has also a non-USB version rwt8822b, so the chip
> for the USB support can also be separate from the main chip, but until
> now don't want to destroy one of the plastic cases.

The driver that many people have been using is the one in 
https://github.com/cilynx/rtl88x2bu.  The driver module is named 
88x2bu.ko; it is a replacement for the rtw88_8822bu driver.

Apparently this has not been merged into the standard Linux kernel 
because Realtek's vendor drivers are not acceptable to the kernel's 
network maintainers.  You might be able to get more information about 
this if you ask on a WLAN mailing list rather than a USB mailing list.

Alan Stern