Re: [RESEND][PATCH] Bluetooth: Make request workqueue freezable

[Takashi Iwai]

At Thu, 21 May 2015 13:37:56 -0400 (EDT),
Alan Stern wrote:
> 
> On Thu, 21 May 2015, Takashi Iwai wrote:
> 
> > At Thu, 21 May 2015 11:26:17 -0400 (EDT),
> > Alan Stern wrote:
> > > 
> > > On Thu, 21 May 2015, Takashi Iwai wrote:
> > > 
> > > > At Thu, 21 May 2015 10:18:08 -0400 (EDT),
> > > > Alan Stern wrote:
> > > > > 
> > > > > On Thu, 21 May 2015, Takashi Iwai wrote:
> > > > > 
> > > > > > Then avoiding the failed firmware is no solution, indeed.
> > > > > > If it's a new probe, it should be never executed during resume.
> > > > > 
> > > > > Can you expand this comment?  What's wrong with probing during resume?
> > > > 
> > > > Well, if the probe requires the access to a user-space file, it can't
> > > > be done during resume.  That's the very problem we're seeing now.
> > > > The firmware loader can't help much alone if it's a new device
> > > > object.
> > > 
> > > But the same thing happens during early boot, if the driver is built 
> > > into the kernel.  When the probe occurs, userspace isn't up and running 
> > > yet, so the firmware loader can't do anything.
> > > 
> > > Why should probe during resume be any worse than probe during early 
> > > boot?
> > 
> > The early boot has initrd, so the files can be there.  But the resume
> > has no way to fetch the file except for cached data.
> 
> I suppose USB could delay re-probing until userspace is running again,
> if we knew when that was.  But it would be awkward and prone to races.  
> It also would leave a user-visible window of time during which the 
> device does not exist, which we want to avoid.  (This may not matter 
> for bluetooth, but it does matter for other kinds of devices.)

Right.

> I would prefer to solve this problem in a different way, if possible.

Well, we're back in square again :)

But, before going further the discussion in loop again, I'd like to
know which firmware file actually hits.  Is it a non-existing
firmware?  Or is it a firmware that should have been cached?  In the
latter case, why it isn't used?


Takashi
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