Re: [PATCH v2 00/24] ARM: zte: Add support for Sanechips ZX279128S and ZTE ZXHN H3600

[Agustin Santiago Isasmendi <isasmendi.agus@gmail.com>]

Hi Navid,

One more finding from testing on my H3600, more serious than the
others: with this series as posted, the board hangs hard as soon as
there is sustained WiFi traffic.

Setup: mt7915e built in, hostapd on the 5 GHz radio bridged with lan1,
a phone uploading to a host on lan1. The first bulk transfer stalls
after a few seconds and the system never comes back: no console, no
oops; only a reset recovers it. 3 boots out of 3, always within the
first transfer.

As far as I can tell from earlier work on this SoC, the cause is an
mt76 register read over PCIe that is outstanding while the PL310
performs a cache maintenance operation, which deadlocks the bus.
Serializing device reads against PL310 maintenance makes the same
test pass on 3 boots out of 3, and a 30 minute mixed WiFi/LAN/WAN
soak runs clean.

I'm preparing that as an RFC for linux-arm-kernel, since it affects
any PCIe device on this SoC, not only your driver. Did you run
sustained traffic over WiFi on your unit, and did you see anything
similar?

Agustin