[FS#105] lantiq: high latency on adsl lines using pppo[ae]

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Alexander Couzens (lynxis) 

Attached to Project - LEDE Project
Summary - lantiq: high latency on adsl lines using pppo[ae]
Task Type - Bug Report
Category - Base system
Status - New
Assigned To - 
Operating System - All
Severity - Medium
Priority - Medium
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - based on the thread 
[LEDE-DEV] [OpenWrt-Devel] latency on PPPoA ADSL Annex A on	using Lantiq

http://lists.infradead.org/pipermail/lede-dev/2016-August/002138.html

When using ssh onto the box via adsl, there is a high latency.
The last 3.18 version of lede works. Known good:

  * 161179f40bd7899516518f3844fea28c6dd86efc r47130

Known broken versions:

  * 2a0e1b7f8d59f795abb29d20007822f0da232c43 r47958

mkresin also has a patch for lantiq+4.0, which also has a high latency.
blogic mentioned linux commit 7424ce65065852bdf7a040bf2490da4a8fc4b464 [atm] switch vcc_sendmsg() to copy_from_iter() could be the issue.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=105