system hang with backports-20150511/20150525

[Michal Kazior]

On 1 June 2015 at 09:13, Kalle Valo <kvalo at qca.qualcomm.com> wrote:
> Michal Kazior <michal.kazior at tieto.com> writes:
>
>> +ath10k list
>>
>> On 1 June 2015 at 03:37, Marty Faltesek <mfaltesek at google.com> wrote:
>>> Starting with backports-20150511, and continuing with
>>> backports-20150525, we see frequent system hangs. backports-20150424
>>> had no issue.
>>
>> I don't see such binary releases on
>> https://backports.wiki.kernel.org/index.php/Main_Page
>> Hence I don't know what kernel you've backported the drivers from and
>> I can't compare anything.
>>
>> Can you provide more details, please?
>
> I suspect it's from here:
>
> https://www.kernel.org/pub/linux/kernel/projects/backports/2015/05/25/
>
> The backports project pages are a bit confusing and that location is
> hard to find.

Oh, thanks!

Hmm.. There was a ton of changes between 20150424 and 20150511. For
one, ath10k started to use chanctx API and FAST_XMIT. But it's not a
given these two are to blame.

The latter can be easily disabled by removing
IEEE80211_HW_SUPPORT_FAST_XMIT from ar->hw->flags in ath10k's mac.c.
The former.. not so easy. I'd be awesome if you could do a git bisect.
The commit ids are a3da0fb6(good) f17107c(bad) (you need linux-next
git repo including its tags for these ids to be resolvable).


Michał