linux-kernel - Re: iwlwifi getting stuck with current Linus' tree (646da63172)

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Message-ID: <1429812611.23202.4.camel@intel.com>
Date:	Thu, 23 Apr 2015 18:10:11 +0000
From:	"Grumbach, Emmanuel" <emmanuel.grumbach@...el.com>
To:	"piotr.karbowski@...il.com" <piotr.karbowski@...il.com>
CC:	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jkosina@...e.cz" <jkosina@...e.cz>,
	"ilw@...ux.intel.com" <ilw@...ux.intel.com>,
	"Berg, Johannes" <johannes.berg@...el.com>
Subject: Re: iwlwifi getting stuck with current Linus' tree (646da63172)

On Thu, 2015-04-23 at 14:48 +0200, Piotr Karbowski wrote:
> Hello,
> 
> On Thu, Apr 23, 2015 at 11:15 AM, Jiri Kosina <jkosina@...e.cz> wrote:
> > On Thu, 23 Apr 2015, Grumbach, Emmanuel wrote:
> >
> >> > I will try it, but I expect the result to be bogus because of this,
> >> > unfortunately.
> >>
> >> I can understand. A few users reported that this bug occurred more
> >> reliably when moving their system, although it seems very weird to me.
> >
> > My "feeling" was that it sometimes was related to start of audio playback,
> > but not 100% relieble either.
> >
> >> > > First question is: Are you sure that 4.0-rc6 was good?
> >> >
> >> > Pretty much, yes. I've been running it for quite some time on this
> >> > machine without any issues. But after updating to current HEAD two days
> >> > ago, the issue triggered like 6 or 7 times already.
> >>
> >> Ok - I will try to look at the PCI commits there although I am not sure
> >> I'll be able to make much sense of them...
> >
> > Thanks,
> 
> i've also started noticing hard system lockups with iwlwifi. What's
> worth noticing is that I've started to see this on 3.19 and I also
> have it on 4.0 kernel thus allow me to report it in this very thread.
> I had over month uptime, untill I've updated iwl ucode, maybe this was
> introduced not by kernel but firmware?. The lockups are random and
> result in hard system lockup, frozen Xorg, screen artifacts/glitches,
> audio playback keeps repeating last second or so of music, sysrq
> cannot handle it as well as auto-reboot after kernel panic does not
> kicks in.
> 

I don't see how the ucode can cause crashes, but a new ucode can make
the driver behave differently (new APIs being available) and that can
cause crashes. Please share any logs you may have.

> The hardware I see this problem on is iwl 7260. The only workaround
> I've found so far was to disable power save via `iw dev wlan0 set
> power_save off` and not a single lockup since. What's rather
> disturbing is that by 'modinfo iwlwifi' it does say that power_save is
> default off, but it is not. I am sure that nothing else enables
> power_save on my system because I don't even have udev, and for the
> test I've also disabled wicd, then simple `modprobe iwlwifi` and `iw
> dev wlan0 get power_save` reports 'on'.

Yeah - I know. This is confusing. This module parameter doesn't affect
7260: it uses iwlmvm module which its own setting. iwlwifi's power_save
parameter serves older devices such as 6205 which you seem to have as
well.
In 6205's case, power save is disabled by default. But all this seems
very far away from the original thread.

> 
> I also have another system iwl 6205 and no single lockup was noted,
> but it indeed have power_save disabled, so that may be the case.
> 
> -- Piotr.