From: Simon Wunderlich <sw@simonwunderlich.de>
To: Felix Fietkau <nbd@nbd.name>
Cc: linux-wireless@vger.kernel.org, kvalo@codeaurora.org
Subject: Re: [PATCH 3/4] ath9k: check for deaf rx path state
Date: Thu, 26 Jan 2017 10:50:19 +0100
Message-ID: <4839692.lfma8z9lJt@prime> (sfid-20170126_105610_526617_D002D8CE)
In-Reply-To: <20170125163654.66431-3-nbd@nbd.name>
References: <20170125163654.66431-1-nbd@nbd.name> <20170125163654.66431-3-nbd@nbd.name>
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Hey Felix,


On Wednesday, January 25, 2017 5:36:53 PM CET Felix Fietkau wrote:
> Various chips occasionally run into a state where the tx path still
> appears to be working normally, but the rx path is deaf.
> 
> There is no known register signature to check for this state explicitly,
> so use the lack of rx interrupts as an indicator.
> 
> This detection is prone to false positives, since a device could also
> simply be in an environment where there are no frames on the air.
> However, in this case doing a reset should be harmless since it's
> obviously not interrupting any real activity. To avoid confusion, call
> the reset counters in this case "Rx path inactive" instead of something
> like "Rx path deaf", since it may not be an indication of a real
> hardware failure.
> 
> Signed-off-by: Felix Fietkau <nbd@nbd.name>

As we observed in the field, it may happen that there are still RX interrupts 
triggered, but just a very low number - in which case I believe your version 
wouldn't fix the problem. Therefore we had a threshold in our original patch 
[1].

We would also appreciate if you can at least briefly mention our work if you 
resend/rework our stuff.

Thank you,
    Simon

[1] https://patchwork.kernel.org/patch/9433621/
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