Subject: Re: brcmfmac signal/interference issues
To: Daniel Drake <drake@endlessm.com>
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From: Arend van Spriel <arend.vanspriel@broadcom.com>
Message-ID: <5AA114A9.8050801@broadcom.com> (sfid-20180308_114714_437626_EBCAC0AE)
Date: Thu, 8 Mar 2018 11:47:05 +0100
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On 2/23/2018 2:49 PM, Daniel Drake wrote:
> On Fri, Feb 23, 2018 at 12:54 PM, Arend van Spriel
> <arend.vanspriel@broadcom.com> wrote:
>> Yup. Windows firmware talks NDIS. If you run 'strings 4345r6rtecdc.bin |
>> tail -1' you can see the firmware build target and it likely has 'ndis' in
>> it.

Hi Daniel,

Bit late response. Sorry.

> 43455c0-roml/sdio-ag-ndis-vista-pktfilter-d0c-pno-aoe-p2p-dhdoid-ndoe-gtkoe-mfp-proptxstatus-dmatxrc-keepalive-ap-ampduretry-pclose-txbf
>
> Yes, ndis. So no easy way to run the same firmware on the 2 OSes.

Indeed. I could try building nearly same firmware target. Can you 
provide the firmware version as well.

Now reading over your orignal email again:

 > If I place both antenna terminals inside the Linux MiniPC case, the
 > Linux pings are bad but the Windows pings are fine.
 >
 > If I place both antenna terminals inside the Windows MiniPC case, it
 > is the same: Linux pings are bad, but the Windows pings are fine.
 >
 > And when the Linux antenna is placed outside of both cases, the Linux
 > pings are fine. I've repeated these tests a handful of times in quick
 > succession to make sure that I'm not going crazy and that this is not
 > a case of the problem intermittency causing misleading results. These
 > findings appear very solid.

So it picks up something in the PC. Some sources of interference that I 
have seen before are USB3 and HDMI. Maybe try to shield those if present 
and see if that helps. The nvram contains sensitivity parameters, but as 
you stated you are using the same nvram for windows and linux for now we 
can rule it out for debugging the issue.

Regards,
Arend