[OpenWrt-Devel] [RFC/RFT PATCH] ath9k: implement kthread entropy collection for AR5008 and AR9002 PHYs.

[Felix Fietkau]

On 2020-02-10 10:44, Rui Salvaterra wrote:
> On Fri, 31 Jan 2020 at 08:12, Felix Fietkau <nbd at nbd.name> wrote:
>>
>> For at least AR5008 and AR9002, but probably also for AR9003 I would
>> like to keep the behavior of collecting entropy only once at driver
>> initialization.
>> Last time I worked on this I noticed that on several chips, sampling
>> entropy during normal operation caused stability issues that were hard
>> to pin down but quite noticeable.
>> I think the benefit of continuous entropy collection is simply not worth
>> the extra cost of potential stability issues and debugging time.
>>
>> - Felix
> 
> Hi again, Felix,
> 
> FWIW, this patch has just survived a whole weekend of rngtest <
> /dev/random on a Buffalo WZR-HP-AG300H (dual AR9002). Output follows:
> 
> root at AP157427:~# rngtest < /dev/random
> rngtest 6.6
> Copyright (c) 2004 by Henrique de Moraes Holschuh
> This is free software; see the source for copying conditions.  There
> is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
> PARTICULAR PURPOSE.
> 
> rngtest: starting FIPS tests...
> ^Crngtest: bits received from input: 224241980032
> rngtest: FIPS 140-2 successes: 11203058
> rngtest: FIPS 140-2 failures: 9041
> rngtest: FIPS 140-2(2001-10-10) Monobit: 1165
> rngtest: FIPS 140-2(2001-10-10) Poker: 1175
> rngtest: FIPS 140-2(2001-10-10) Runs: 3340
> rngtest: FIPS 140-2(2001-10-10) Long run: 3405
> rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
> rngtest: input channel speed: (min=165.459; avg=1025.932; max=1093.147)Kibits/s
> rngtest: FIPS tests speed: (min=503.707; avg=14584.165; max=14920.741)Kibits/s
> rngtest: Program run time: 228508694816 microseconds
The issues that were reported years ago were mainly stuck beacons,
increase in hardware resets, connection stability issues.

- Felix

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