Re: More than one ath10k NIC will not load (bisected)

From: Michal Kazior <michal.kazior@tieto.com>
To: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Ben Greear <greearb@candelatech.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: More than one ath10k NIC will not load (bisected)
Date: Wed, 4 Feb 2015 10:35:41 +0100	[thread overview]
Message-ID: <CA+BoTQmGWLDHGa=GkhtDaSupsY-nd5e5nUuwg6iMAN4d8WjOTA@mail.gmail.com> (raw)
In-Reply-To: <87vbjit58l.fsf@kamboji.qca.qualcomm.com>

On 4 February 2015 at 10:07, Kalle Valo <kvalo@qca.qualcomm.com> wrote:
> Ben Greear <greearb@candelatech.com> writes:
>
>>> Hmm.. This removes warm_reset in probe function but I fail to see how
>>> this could end up not loading one of the NIC *silently*?
>>>
>>> Anyway there's a pending patch which adds the reset back:
>>> https://github.com/kvalo/ath/commit/bdcd6f4e4ac5d2d2a56da4813f56655e6db0ee45
>>> . You might want to try it and see if it helps.
>>
>> Reverting the patch made it work again for me.
>>
>> I don't understand that code well, but perhaps you are disabling
>> a shared interrupt that silently stops the second NIC from
>> being able to do it's thing?
>>
>> Do you have a PC with 2 NICs in it that you could try yourself?
>>
>> I can grab you the logs of a failure to boot later today.
>
> What should we do with this one? I didn't look at the details yet, but
> do we have any other option than to revert?

I believe this is an issue in Ben's userspace (he sent me logs
privately) or some sort of kernel event bug. It basically looked like
this: both devices were detected by ath10k and both started
register_work. One of the devices loaded all the way while the other
tried to load a few non-existing firmware files and it stopped. Few
minutes later there was a hung task splat pointing to
request_firmware() called from ath10k suggesting userspace didn't
handle firmware request.

The "offending" patch effectively removed 200ms from probe() in
ath10k. This could've change timing on request_firmware() calls on
Ben's system. Btw. the 200ms is back again now with
1a7fecb766c83dace747f42b25bbb544b00a0163 ("ath10k: reset chip before
reading chip_id in probe").

Marek tried running 2 qca988x on his laptop some time ago (with and
without the extra timing) and didn't have any issues.

Michał

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