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Date:   Mon, 01 Mar 2021 13:31:34 +0000
From:   Marc Zyngier <maz@kernel.org>
To:     Frank Wunderlich <frank-w@public-files.de>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Thierry Reding <treding@nvidia.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Rob Herring <robh@kernel.org>, Will Deacon <will@kernel.org>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Ryder Lee <ryder.lee@mediatek.com>,
        Marek Vasut <marek.vasut+renesas@gmail.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        Michal Simek <michal.simek@xilinx.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-hyperv@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-renesas-soc@vger.kernel.org
Subject: Re: Aw: Re:  [PATCH 09/13] PCI: mediatek: Advertise lack of MSI
 handling
In-Reply-To: <trinity-9fa6d24e-f9de-4741-bf44-86f6197b174d-1614600961297@3c-app-gmx-bap67>
References: <20210225151023.3642391-1-maz@kernel.org>
 <20210225151023.3642391-10-maz@kernel.org>
 <trinity-b7e2cf18-f0e6-4d88-8a80-de6758b5a91f-1614595396771@3c-app-gmx-bap67>
 <b7721e2ff751cc9565a662cb713819e3@kernel.org>
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Frank,

>> > i guess it's a bug in ath10k driver or my r64 board (it is a v1.1
>> > which has missing capacitors on tx lines).
>> 
>> No, this definitely looks like a bug in the MTK PCIe driver,
>> where the mutex is either not properly initialised, corrupted,
>> or the wrong pointer is passed.
> 
> but why does it happen only with the ath10k-card and not the mt7612 in
> same slot?

Does mt7612 use MSI? What we have here is a bogus mutex in the
MTK PCIe driver, and the only way not to get there would be
to avoid using MSIs.

> 
>> This r64 machine is supposed to have working MSIs, right?
> 
> imho mt7622 have working MSI
> 
>> Do you get the same issue without this series?
> 
> tested 5.11.0 [1] without this series (but with your/thomas' patch
> from discussion about my old patch) and got same trace. so this series
> does not break anything here.

Can you retest without any additional patch on top of 5.11?
These two patches only affect platforms that do *not* have MSIs at all.

> 
>> > Tried with an mt7612e, this seems to work without any errors.
>> >
>> > so for mt7622/mt7623
>> >
>> > Tested-by: Frank Wunderlich <frank-w@public-files.de>
>> 
>> We definitely need to understand the above.
> 
> there is a hardware-bug which may cause this...afair i saw this with
> the card in r64 with earlier Kernel-versions where other cards work
> (like the mt7612e).

I don't think a HW bug affecting PCI would cause what we are seeing
here, unless it results in memory corruption.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...