Re: Regression with dell-rbtn: radio killed on resume after suspend to RAM

[Darren Hart <dvhart@infradead.org>]

On Mon, Nov 23, 2015 at 07:23:29PM +0300, Andrei Borzenkov wrote:
> 23.11.2015 18:14, Gabriele Mazzotta пишет:
> >On 23/11/2015 15:50, Pali Rohár wrote:
> >>On Sunday 22 November 2015 09:23:19 Andrei Borzenkov wrote:
> >>>21.11.2015 23:39, Andrei Borzenkov пишет:
> >>>>21.11.2015 22:08, Pali Rohár пишет:
> >>>>>On Saturday 21 November 2015 19:57:18 Andrei Borzenkov wrote:
> >>>>>>After installing 4.2 on Dell Latitude E5450 I found that wireless was
> >>>>>>disabled every second resume from suspend to RAM. Blacklisting
> >>>>>>dell-rbtn "fixed" it.
> >>>>>>
> >>>>>>This is probably the same as discussed in this Arch forum and related
> >>>>>>bug report: https://bbs.archlinux.org/viewtopic.php?id=203404. I
> >>>>>>myself hit it on Ubuntu.
> >>>>>>
> >>>>>>I am not familiar with other models, but E5450 does have DELLABCE and
> >>>>>>so is using dell-rbtn driver.
> >>>>>>
> >>>>>>I am happy to test patches if need. Please let me know if formal bug
> >>>>>>report is required.
> >>>>>>
> >>>>>>-andrei
> >>>>>
> >>>>>Hi Andrei!
> >>>>>
> >>>>>About five hours ago Gabriele sent patch which fixing this problem to
> >>>>>LKML. You can find it on: https://lkml.org/lkml/2015/11/21/57
> >>>>>
> >>>>>Can you test that patch and confirm it fix also for you?
> >>>>>
> >>>>
> >>>>Yes, it does.
> >>>
> >>>Unfortunately it was too early. Today after resume I again got disable
> >>>radio, and also several later attempts to suspend/resume. Then last
> >>>time I
> >>>suddenly got radio working again after resume.
> >>>
> >>>Patch looks racy; there is no guarantee we get notification before
> >>>resetting
> >>>in suspend flag.
> >>>
> >>
> >>Gabriele, any idea how to fix this?
> >>
> >
> >I can't think of anything other than ignoring notifications that arrives
> >within X seconds after the execution of the resume callback.
> >Unfortunately, we have no idea on how to detect systems that misbehave
> >and creating a blacklist is not a feasible solution.
> >
> >Something such as the following should work, but maybe it's not a nice
> >solution.
> >
> 
> I looked at what dell-rbtn does. My system (Latitude E5450) has RBTN of type
> TOGGLE. In this case both del-laptop hooks itself into i8042 and dell-rbtn
> delivers KEY_RFKILL event to input susbsystem. IOW dell-rbtn looks
> completely redundant in this configuration.
> 
> Can we detect that rfkill toggle is already avaiable via normal keyboard and
> not activate dell-rbtn in this case?

Also dropping this one until we can arrive at a complete solution.

Pali, Gabriele, this one is in your hands. I will review and provide feedback
where I can - I confess I'm finding it difficult to keep all the pieces straight
in my head, and without any hardware, I have to rely entirely on what I can
piece together (a situation we are all in as this differs across many systems,
nobody has all the necessary bits).

It may be helpful for someone to put together a current status, known issues,
plan of attack to get this moving forward again.

-- 
Darren Hart
Intel Open Source Technology Center