Re: USB rndis_host - slow download transfers, RX errors

[Tomasz Janowski <tomasz.janowski-4+jYJfmkT58@public.gmane.org>]

On Thursday, February 8, 2018 3:43:05 PM EST Greg KH wrote:
> 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.

The error messages which I have attached were produced by a precompiled Debian 
kernel: "Linux version 4.14.0-0.bpo.3-amd64 (debian-kernel-0aAXYlwwYIJuHlm7Suoebg@public.gmane.org) 
(gcc version 6.3.0 20170516 (Debian 6.3.0-18)) #1 SMP Debian 4.14.13-1~bpo9+1 
(2018-01-14)".

But I have downloaded the most recent version of the kernel from the official 
git repository (last commit: Jan 31, 2018) and it had exactly the same 
problem. Unless a patch was submitted within the last week, the issue is still 
there.

Should I get the version as of today and test it again?

Thanks!
Tomasz


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