Re: Problem with 9984 in routed mode with 512b frames.

From: Ben Greear <greearb@candelatech.com>
To: Sebastian Gottschall <s.gottschall@newmedia-net.de>,
	ath10k <ath10k@lists.infradead.org>
Subject: Re: Problem with 9984 in routed mode with 512b frames.
Date: Thu, 16 May 2019 12:40:14 -0700	[thread overview]
Message-ID: <55b50a9a-49f4-d669-22d4-84e2efabf451@candelatech.com> (raw)
In-Reply-To: <ad97576c-d6dd-e29c-10d4-00b8aff77805@candelatech.com>

On 5/15/19 6:00 AM, Ben Greear wrote:
> On 5/15/19 5:26 AM, Sebastian Gottschall wrote:
>>
>> Am 15.05.2019 um 14:20 schrieb Ben Greear:
>>> On 05/14/2019 09:26 PM, Sebastian Gottschall wrote:
>>>> can you send me a detailed instruction for testing this on my devices? so which commands have been used for generating the traffic etc. (iperf3?)
>>>
>>> I am using our own traffic generator, but I imagine iperf3 should work fine too.
>>>
>>> I am testing on x86-64 and so forth.  Maybe you can test with UDP small-packet load on your platform
>>> in routed mode (ie, external iperf generator through your AP) and see if you see issues?
>> thats the plan. can you do a test with iperf3 to see if its reproduceable. i mean i will test it on ipq based boards and x64. but to make sure that the scenario
>> is identical which raised up your issue, it would be find if we have identical software for testing including the same options

I think I found the issue.  The rate-ctrl logic in the firmware allows a transition from HT/VHT 20 MCS0 down to OFDM rates.
It seems the hardware does not like to see an AMPDU with an OFDM rate for 20Mhz and a VHT rate for 80Mhz (or maybe just the
single OFDM rate is the fault).

If you can edit firmware, then setting this to 0 probably fixes the issue.

g_rc_cck_rate_allowed

I think to reproduce you'd need to send high speed traffic in a situation where the
RF environment is going to make rate-ctrl fail quite a bit.  (Slow speed should
work too, but it would likely take a lot longer).

And, it is always possible that whatever I saw when testing mostly-stock FW is different
from what I eventually debugged to in my firmware.  Still, from looking at MCS vs SNR
charts, there seems to be no advantage to trying OFDM vs MCS0 for 20Mhz.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

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