Re: USB rndis_host - slow download transfers, RX errors

[Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>]

On Thu, Feb 08, 2018 at 02:16:08PM +0000, Tomasz Janowski, Ph.D. wrote:
> Dear USB developers,
> 
> Based on my google research, the problem I experience seems to happen
> with some newer smartphones. My test case is Samsung Galaxy S8 (SM-950U1). I am
> trying to use USB tethering and everything seems to work as expected (modules
> are loaded, Ethernet devices are up and running, dhcp works fine). I can connect to
> the external world using both LTE or wireless network on the phone.
> 
> Now, the problem is that the download speeds are terrible, around 64 KB/s,
> while uploads are fast, the order of 15 MB/s. These speeds do not depend
> on the wireless service provider: the results are similar when I tether wi-fi.
> The USB Ethernet interface on the Linux host reports a lot of receive errors (attached:
> device_state.txt), while kernel reports bad rndis messages (attached: kernel.log.txt).
> 
> Windows 10 works great with the same hardware (same PC and same phone), with
> uploads and downloads in the order of 150 Mbit/s, which is probably as fast as my
> wireless network can do. But some people reported issues with older Windows drivers too.
> Is possible that some newer version of RNDIS protocol is around and Linux hasn't updated
> its RNDIS module yet?

Hey, I was _just_ talking to someone at Google about this same issue
yesterday, you beat him sending this same type of report to the mailing
list, nice job :)

Yes, this is not good, and we should work to resolve this, but first,
what kernel version are you using?  I think some fixes for the rndis
driver went in recently to 4.15, but it would be good to verify that
this isn't already resolved.

thanks,

greg k-h
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