# Re: Aw: Re: \[PATCH 09/13\] PCI: mediatek: Advertise lack of MSI handling

- From: Marc Zyngier \<maz@kernel.org\>
- Date: 2021-03-01 13:32:59 
- List: linux-hyperv
- Page: https://ratatoskr.run/linux-hyperv/2021/03/6281508
- Thread: https://ratatoskr.run/linux-pci/2021/02/6278957/t.md

```text
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 <redacted>
>>
>> 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...
```