Re: [PATCH] Revert "Revert "wifi: ath11k: Enable threaded NAPI""

From: Manikanta Pubbisetty
Date: Thu Aug 10 2023 - 00:47:02 EST




On 8/9/2023 2:46 PM, Johan Hovold wrote:
On Wed, Aug 09, 2023 at 02:32:37PM +0530, Manikanta Pubbisetty wrote:
On 8/9/2023 1:04 PM, Johan Hovold wrote:
This reverts commit d265ebe41c911314bd273c218a37088835959fa1.

Disabling threaded NAPI causes the Lenovo ThinkPad X13s to hang (e.g. no
more interrupts received) almost immediately during RX.

Apparently something broke since commit 13aa2fb692d3 ("wifi: ath11k:
Enable threaded NAPI") so that a simple revert is no longer possible.


This is getting as weird as it would get :)

As commit d265ebe41c91 ("Revert "wifi: ath11k: Enable threaded NAPI"")
does not address the underlying issue reported with QCN9074, it seems we
need to reenable threaded NAPI before fixing both bugs properly.


It seems that the revert has actually solved the issue reported with
QCN9074.

https://bugzilla.kernel.org/show_bug.cgi?id=217536

Sure, but it's only a workaround as the underlying cause has not been
identified.

We were trying to reproduce the problem on X86+QCN9074 (with threaded
NAPI) from quite some time, but there is no repro yet.

Actually, enabling/disabling threaded NAPI is a simple affair; I'm
wondering to hear that interrupts are blocked due to not having
threaded NAPI.

It sounds to me like the driver's locking is broken if moving to softirq
processing hangs the machine like this. But I have not had time to try
to try to track it down besides verifying that reenabling threaded NAPI
makes the problem go away.

What is the chip that Lenovo Thinkpad X13s is having?

It's a WCN6855 (QCNFA765).


Also it is worth to give a try with this patch here https://patchwork.kernel.org/project/linux-wireless/patch/20230601033840.2997-1-quic_bqiang@xxxxxxxxxxx/ . This seems to be fixing some known interrupt issue on WCN6855. Could you pls give a try?

Thanks,
Manikanta