Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
To:     Luca Coelho <luciano.coelho@intel.com>
Cc:     linux-wireless@vger.kernel.org, Marek Vasut <marex@denx.de>
From:   Claudius Heine <ch@denx.de>
Subject: Operating Intel Wireless-AC 9260 with one antenna (iwlmvm)
Organization: Denx Software Engineering
Message-ID: <ada8f488-fdab-b421-7376-78e5fc403f4b@denx.de>
Date:   Thu, 7 Oct 2021 11:53:44 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.14.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Luca Coelho,

the available documentation [1] [2] on the Intel Wireless-AC 9260 
doesn't explicitly state that operating it with just one antenna is 
impossible, just that it would be necessary for optimal performance.

Operating that module with wifi-only and just one antenna connected 
seems to work somewhat ok, but we had some deauth issues, which could be 
unrelated.

Operating both wifi+bt with just one antenna, makes wifi loose packages 
while bt is active. I hard-coded the `valid_{t,r}x_ant` to `1` in the 
nvm parser code, which seem to improve this issue somewhat, but bt 
pairing seems to be unstable.

But the general question is: Is that module even designed to operate 
with just one antenna connected and are wifi and bt issues to be 
expected in that case? Bt would not be strictly required in our use-case.

If it should work with just one antenna, do you know of any available 
tools to create those nvm image files or overwrite the nvm with the 
correct antenna configuration? Or is there another way for this to be 
configured?

Thanks a lot and kind regards,
Claudius Heine

[1] 
https://www.intel.com/content/www/us/en/support/articles/000031221/wireless.html
[2] 
https://www.intel.com/content/dam/support/us/en/documents/network-and-i-o/wireless-networking/intel-wifi-adapter-information-guide.pdf