Re: MMC/regulator boot hang in -next

From: John Stultz
Date: Mon Nov 02 2015 - 17:27:10 EST

On Mon, Nov 2, 2015 at 2:03 PM, John Stultz <john.stultz@xxxxxxxxxx> wrote:
> On Mon, Nov 2, 2015 at 12:46 PM, Bjorn Andersson
> <bjorn.andersson@xxxxxxxxxxxxxx> wrote:
>> On Mon 02 Nov 11:57 PST 2015, John Stultz wrote:
>>> Trying to move my nexus7 work to -next, I started seeing boot time
>>> hangs. Enabling some debug options provided with a lockdep spew.
>>> Reverting "regulator: core: Propagate voltage changes to supply
>>> regulators" - fc42112c0eaa avoids the hang, but I still see lockdep
>>> noise.
>>> Full log of -next based tree without any reverts follows:
>> It sure does lock like a deadlock to me. Can you figure out which
>> regulator we're talking about here? And confirm that this is 8064 we're
>> talking about
> So it looks like we're setting the voltage on lvs1, which then calls
> get_voltage() on s4. At that point the lockdep spew hits.
> But as Mark noted *this* spew looks like a false positive, but I
> suspect lockdep is then disabled and can't detect the real hang
> happens shortly afterwards.

Further on this, the lockdep spew happens w/ v4.3 as well. Its just
the deadlock in -next got me to add lockdep in my config.

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