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Re: brcmfmac signal/interference issues

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On 3/8/2018 4:54 PM, Steve deRosier wrote:
On Thu, Mar 8, 2018 at 2:47 AM, Arend van Spriel
<arend.vanspriel@xxxxxxxxxxxx> wrote:
On 2/23/2018 2:49 PM, Daniel Drake wrote:

On Fri, Feb 23, 2018 at 12:54 PM, Arend van Spriel
<arend.vanspriel@xxxxxxxxxxxx> 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.


Hi Daniel,

I'll jump in here too...

Did you check the Bluetooth?  I don't know if this chip has it or if
it's an independent chip on this board, but if Linux is leaving it
powered up but not properly configured you could have issues. And in
some designs, the BT and WiFi will share a single antenna. Note that
I'm not saying you've configured BT to run, I'm actually suggesting
that the pin that enables it is on, but you might not be loading the
BT drivers and firmware and so the thing is just in a wonky
uninitialized state. Or you do have it enabled and should try turning
it off.  Either way.

And WiFi/BT coex has always been a bit of a problem (speaking
generally, I don't know the status with this particular chip) in
Linux. I see WiFi and BT interfering with each other frequently in my
testing setups with my dev boards. Often I can magically make problems
go away by simply pulling the enable line high (which is "off").

Thanks, Steve

Disabling BT was indeed suggested, but indeed pulling BT_REG_ON high will ensure there is nothing active on BT side. In BT the firmware is generally speaking on-chip with possibility to download firmware patch to the device. However, if no driver does hci initialization I would expect BT to be passive/silent, but I guess your magic proves otherwise ;-)

Regards,
Arend




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