iMX6 PCIE IRQ not working with ath9k based Wifi

[Lucas Stach]

Hi Mike,

Am Montag, den 09.10.2017, 12:56 +0100 schrieb Mike Tubby:

[...]

> If I understand correctly the ath9k driver in kernel 4.1.15 we're
> using 
> doesn't enable MSI - so I assume that there is some backwards 
> compatibility mode that then is not working because MSI is enabled
> at 
> the CPU end, and hence the patch you referred to is used to turn this
> off.
> 
> At the same time on the mailing list:
> 
> https://www.mail-archive.com/ath9k-devel@lists.ath9k.org/msg14332.htm
> l
> 
> which is part of:
> 
>      https://wireless.wiki.kernel.org/en/users/Drivers/ath9k
> 
> there is talk of a patch to the ath9k driver to properly implement
> MSI 
> in the updated driver in kernel 4.6
> 
> So, for us the question is which way to head:
> 
>      a) disable MSI at the CPU and try to use legacy; or
> 
>      b) update the ath9k driver to try and enable MSI ?
> 
> 
> We will also check the DTS/DTB in case something is mis-assigned.

Due to a design flaw of the DWC host controller, legacy IRQs (like the
ones used by ath9k) won't work if any MSIs are enabled on the
controller.

You can take a look at my series "[PATCH 0/3] DWC host without MSI
controller", which works around this, but still needs some rework for
mainline.

Regards,
Lucas