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Date:   Thu, 20 May 2021 10:38:12 -0700
From:   Bhaumik Bhatt <bbhatt@codeaurora.org>
To:     Kalle Valo <kvalo@codeaurora.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Greg KH <gregkh@linuxfoundation.org>
Cc:     Loic Poulain <loic.poulain@linaro.org>, ath11k@lists.infradead.org,
        linux-wireless@vger.kernel.org, regressions@lists.linux.dev,
        stable@vger.kernel.org
Subject: Re: [regressions] ath11k: v5.12.3 mhi regression
Organization: Qualcomm Innovation Center, Inc.
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On 2021-05-20 05:36 AM, Kalle Valo wrote:
> Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> writes:
> 
>> On Thu, May 20, 2021 at 12:02:40PM +0200, Greg KH wrote:
>>> On Thu, May 20, 2021 at 12:47:53PM +0300, Kalle Valo wrote:
>>> > Hi,
>>> >
>>> > I got several reports that this mhi commit broke ath11k in v5.12.3:
>>> >
>>> > commit 29b9829718c5e9bd68fc1c652f5e0ba9b9a64fed
>>> > Author: Bhaumik Bhatt <bbhatt@codeaurora.org>
>>> > Date:   Wed Feb 24 15:23:04 2021 -0800
>>> >
>>> >     bus: mhi: core: Process execution environment changes serially
>>> >
>>> >     [ Upstream commit ef2126c4e2ea2b92f543fae00a2a0332e4573c48 ]
>>> >
>>> > Here are the reports:
>>> >
>>> > https://bugzilla.kernel.org/show_bug.cgi?id=213055
>>> >
>>> > https://bugzilla.kernel.org/show_bug.cgi?id=212187
>>> >
>>> > https://bugs.archlinux.org/task/70849?project=1&string=linux
>>> >
>>> > Interestingly v5.13-rc1 seems to work fine, at least for me, though I
>>> > have not tested v5.12.3 myself. Can someone revert this commit in the
>>> > stable release so that people get their wifi working again, please?
>>> 
>>> How does the mhi bus code relate to a ath11k driver?  What bus is 
>>> that
>>> on?
>>> 
>> 
>> MHI is the transport used by the ath11k driver to work with the WLAN 
>> devices
>> over PCIe.
>> 
>> Regarding the bug, I'd suggest to wait for Bhaumik (the author of 
>> 29b9829718c5)
>> to comment on the possible commit which needs backporting from 
>> mainline.
> 
> Ok, but if a quick fix is not available I think we should just revert
> this in the stable releases. I also got a report that v5.11.21 is
> broken:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=213055#c11

Please pick [1] as the dependency to [ Upstream commit 
ef2126c4e2ea2b92f543fae00a2a0332e4573c48 ].

That is missing in older kernels and did not get backported.
This explains why 5.13.x works.

Thanks,
Bhaumik
---
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[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/bus/mhi/core?h=v5.13-rc2&id=4884362f6977fc05cbec736625665241c0e0732f