iwlwifi: AX201 not using 2 receive streams

iwlwifi: AX201 not using 2 receive streams

[Brandon Nielsen]

I have a system with Intel AX201 not using 2 spatial streams in the RX 
(download) direction. TX (upload) functions as expected. I'm seeing 
similar behavior with an AX200 system. I'm seeing the same behavior on 
5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. 
Windows works as expected.

I have opened bug 215465[0] with some more detail.

[0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465

Re: iwlwifi: AX201 not using 2 receive streams

[Ben Greear]

On 1/8/22 12:50 PM, Brandon Nielsen wrote:
> I have a system with Intel AX201 not using 2 spatial streams in the RX (download) direction. TX (upload) functions as expected. I'm seeing similar behavior with 
> an AX200 system. I'm seeing the same behavior on 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. Windows works as expected.
> 
> I have opened bug 215465[0] with some more detail.
> 
> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465
> 

We saw something similar with ax210, but only on 6E, in kernel 5.15.7+.  On 5Ghz, it worked 2x2 as expected.
On a 5.15.0-rc something, it worked OK for us.

We verified same firmware is used in both cases, but have not fully bisected the problem yet but we are
working on it.  In case you find the problem patch before us, please let me know!

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: iwlwifi: AX201 not using 2 receive streams

[Brandon Nielsen]

On 1/8/22 3:22 PM, Ben Greear wrote:
> On 1/8/22 12:50 PM, Brandon Nielsen wrote:
>> I have a system with Intel AX201 not using 2 spatial streams in the RX 
>> (download) direction. TX (upload) functions as expected. I'm seeing 
>> similar behavior with an AX200 system. I'm seeing the same behavior on 
>> 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. 
>> Windows works as expected.
>>
>> I have opened bug 215465[0] with some more detail.
>>
>> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465
>>
> 
> We saw something similar with ax210, but only on 6E, in kernel 5.15.7+.  
> On 5Ghz, it worked 2x2 as expected.
> On a 5.15.0-rc something, it worked OK for us.
> 
> We verified same firmware is used in both cases, but have not fully 
> bisected the problem yet but we are
> working on it.  In case you find the problem patch before us, please let 
> me know!
> 
> Thanks,
> Ben
> 

I'm still seeing this as far back as 5.11.12, so I'm not convinced this 
is a regression. At least for the 5 GHz / 802.11ac case.

Re: iwlwifi: AX201 not using 2 receive streams

[Ben Greear]

On 1/11/22 11:46 AM, Brandon Nielsen wrote:
> On 1/8/22 3:22 PM, Ben Greear wrote:
>> On 1/8/22 12:50 PM, Brandon Nielsen wrote:
>>> I have a system with Intel AX201 not using 2 spatial streams in the RX (download) direction. TX (upload) functions as expected. I'm seeing similar behavior 
>>> with an AX200 system. I'm seeing the same behavior on 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. Windows works as expected.
>>>
>>> I have opened bug 215465[0] with some more detail.
>>>
>>> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465
>>>
>>
>> We saw something similar with ax210, but only on 6E, in kernel 5.15.7+. On 5Ghz, it worked 2x2 as expected.
>> On a 5.15.0-rc something, it worked OK for us.
>>
>> We verified same firmware is used in both cases, but have not fully bisected the problem yet but we are
>> working on it.  In case you find the problem patch before us, please let me know!
>>
>> Thanks,
>> Ben
>>
> 
> I'm still seeing this as far back as 5.11.12, so I'm not convinced this is a regression. At least for the 5 GHz / 802.11ac case.
> 

Ok, we are trying to bisect now...slow going as normal.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: iwlwifi: AX201 not using 2 receive streams

[Ben Greear]

On 1/11/22 11:46 AM, Brandon Nielsen wrote:
> On 1/8/22 3:22 PM, Ben Greear wrote:
>> On 1/8/22 12:50 PM, Brandon Nielsen wrote:
>>> I have a system with Intel AX201 not using 2 spatial streams in the RX (download) direction. TX (upload) functions as expected. I'm seeing similar behavior 
>>> with an AX200 system. I'm seeing the same behavior on 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. Windows works as expected.
>>>
>>> I have opened bug 215465[0] with some more detail.
>>>
>>> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465
>>>
>>
>> We saw something similar with ax210, but only on 6E, in kernel 5.15.7+. On 5Ghz, it worked 2x2 as expected.
>> On a 5.15.0-rc something, it worked OK for us.
>>
>> We verified same firmware is used in both cases, but have not fully bisected the problem yet but we are
>> working on it.  In case you find the problem patch before us, please let me know!
>>
>> Thanks,
>> Ben
>>
> 
> I'm still seeing this as far back as 5.11.12, so I'm not convinced this is a regression. At least for the 5 GHz / 802.11ac case.
> 

Our engineer Chuck Rekierre bisected the problem we saw to a patch that came in as part of a stable patch.

Please see his revert patch: [PATCH] Revert "iwlwifi: mvm: disable RX-diversity in powersave"
posted yesterday, and if you get a chance to test this, please let us know the results.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: iwlwifi: AX201 not using 2 receive streams

[Brandon Nielsen]

On 1/13/22 11:12 AM, Ben Greear wrote:
> On 1/11/22 11:46 AM, Brandon Nielsen wrote:
>> On 1/8/22 3:22 PM, Ben Greear wrote:
>>> On 1/8/22 12:50 PM, Brandon Nielsen wrote:
>>>> I have a system with Intel AX201 not using 2 spatial streams in the 
>>>> RX (download) direction. TX (upload) functions as expected. I'm 
>>>> seeing similar behavior with an AX200 system. I'm seeing the same 
>>>> behavior on 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a 
>>>> regression. Windows works as expected.
>>>>
>>>> I have opened bug 215465[0] with some more detail.
>>>>
>>>> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465
>>>>
>>>
>>> We saw something similar with ax210, but only on 6E, in kernel 
>>> 5.15.7+. On 5Ghz, it worked 2x2 as expected.
>>> On a 5.15.0-rc something, it worked OK for us.
>>>
>>> We verified same firmware is used in both cases, but have not fully 
>>> bisected the problem yet but we are
>>> working on it.  In case you find the problem patch before us, please 
>>> let me know!
>>>
>>> Thanks,
>>> Ben
>>>
>>
>> I'm still seeing this as far back as 5.11.12, so I'm not convinced 
>> this is a regression. At least for the 5 GHz / 802.11ac case.
>>
> 
> Our engineer Chuck Rekierre bisected the problem we saw to a patch that 
> came in as part of a stable patch.
> 
> Please see his revert patch: [PATCH] Revert "iwlwifi: mvm: disable 
> RX-diversity in powersave"
> posted yesterday, and if you get a chance to test this, please let us 
> know the results.
> 
> Thanks,
> Ben
> 

Just tried it on one of the AX200 systems exhibiting the issue. No 
change. Rock solid MCS 9, but no engagement of the second RX stream.

Re: iwlwifi: AX201 not using 2 receive streams

[Brandon Nielsen]

On 1/8/22 2:50 PM, Brandon Nielsen wrote:
> I have a system with Intel AX201 not using 2 spatial streams in the RX 
> (download) direction. TX (upload) functions as expected. I'm seeing 
> similar behavior with an AX200 system. I'm seeing the same behavior on 
> 5.15.12 as I am with 5.16.0-rc8 so I didn't mark it as a regression. 
> Windows works as expected.
> 
> I have opened bug 215465[0] with some more detail.
> 
> [0] - https://bugzilla.kernel.org/show_bug.cgi?id=215465

Adding luciano.coelho@intel.com to CC.

Let me know if there is more helpful diagnostic information I can provide.