From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wojciech Dubowik <Wojciech.Dubowik@neratec.com>
Date: Tue, 15 Dec 2015 09:30:19 +0100
Subject: [ath9k-devel] NF calibration and software level simulation of
 packet errors
In-Reply-To: <49310F74-314C-40AC-92EB-4CBDF35953E0@ieiit.cnr.it>
References: <49310F74-314C-40AC-92EB-4CBDF35953E0@ieiit.cnr.it>
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To: ath9k-devel@lists.ath9k.org

>
> Is this possible with ath9k? I cannot find any solution by myself. And 
> the NOACK flag is not an option, since I am testing on rate adaptation 
> techniques, so I need varying speeds and ACKs definitely.
You could use
REG_SET_BIT(ah, AR_DIAG_SW, AR_DIAG_ACK_DIS);
to disable or
REG_CLR_BIT(ah, AR_DIAG_SW, AR_DIAG_ACK_DIS);
to enable ACK's on per packet basis. I use it sometimes to verify retries.
>
> I have actually forced a periodic calibration, but I don?t know if it 
> is the correct way of doing.
> Moreover, I discovered NF calibration takes nearly 20 ms. Can you 
> confirm this? Is there a way to have a quicker behavior?
>
It takes  more or less 20ms and it's dependent of numer of silent 
periods and channel bandwidth. If you have constant noise then
driver will adapt to it an set a noise floor to that value. RSSI is will 
be of course wrong on the absolute scale as it's always relative to NF.
Only way I know to speed it up is to calibrate NF on each 
channel/bandwidth/temperature/environment for a specific card and use it 
instead of
measured value. The problem is that CCA is not according to the 
regulations as you don't really care what happens on the channel.

I hope it helps,
Wojtek