Re: [v2] ath9k: add MSI support

[Kalle Valo <kvalo@qca.qualcomm.com>]

(Adding AceLan)

Daniel Drake <drake@endlessm.com> writes:

> On Wed, Nov 15, 2017 at 7:38 AM, Daniel Drake <drake@endlessm.com> wrote:
>> On Tue, Nov 14, 2017 at 8:15 PM, Kalle Valo <kvalo@qca.qualcomm.com> wro=
te:
>>>> Can't be fixed in firmware, but it would be good to have confirmation
>>>> of the hardware behavivour, and maybe some other solution is possible?
>>>> Are you following this up within Qualcomm?
>>>
>>> No time to do that right now, sorry.
>>
>> I got several autoresponders from people on this thread from Qualcomm
>> Taiwan. Would it be useful for us to drop off a sample of the affected
>> product at your Taipei or Hsinchu office so that you can investigate
>> further?
>
> Ping - how can we collaborate on this?

Are you asking me? While looking at my todo list for this year I doubt I
can find time to help with the MSI implementation or bugfixing.

But my plan is that first I would apply Russel's patch which makes it
possible to enable MSI with a module parameter:

https://patchwork.kernel.org/patch/9999249/

Then if AceLan could rebase the quirk patches and resubmit those so that
I can apply those:

https://patchwork.kernel.org/patch/9971097/
https://patchwork.kernel.org/patch/9971095/
https://patchwork.kernel.org/patch/9971093/
https://patchwork.kernel.org/patch/9971091/
https://patchwork.kernel.org/patch/9971089/

Also I don't see the need to have five different patches for the quirks,
having just one patch adding all those should be ok.

Are everyone happy with this plan?

> Also, we have been testing the MSI support patch and while it seems to
> be working fine on AR9565, multiple users hit failures on AR9462. The
> most common report is that the system simply cannot maintain the
> connection with the AP for more than a few seconds. It hits a check in
> mac80211 where it sends a nullfunc to the AP and expects an ack in
> less than 500ms, but it disconnects since it doesn't see the ack.
>
> https://marc.info/?l=3Dlinux-wireless&m=3D151027741010422&w=3D2
>
> We also reproduced a problem in our office with AR9462. With the MSI
> support patch in use, we ping a server every second for 1000 seconds
> while monitoring "iw dev wlp2s0 link" output. With the MSI support
> patch in place, this test fails every time; the connection is dropped
> in less than 1000s.
> With the patch reverted everything is fine.

I'm not really surprised and this is exactly why I was against of
enabling MSI by default. It can cause all sorts of weird problems.

--=20
Kalle Valo=