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Date: Wed, 22 May 2013 10:53:38 +0200
From: Stephan Gatzka <stephan.gatzka@gmail.com>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Peter Hurley <peter@hurleysoftware.com>,
        linux1394-devel@lists.sourceforge.net, Tejun Heo <tj@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: function call =?UTF-8?Q?fw=5Fiso=5Fresource=5Fmange=28=2E=2E?=
 =?UTF-8?Q?=29=20=28core-iso=2Ec=29=20does=20not=20return?=
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> I am a friend of the self-ID-complete worklet, for two reasons:
>   - Even if there was no need for the TI TSB41BA3D workaround (e.g. 
> even
>     if we simply stopped supporting TSB41BA3D), it would still be
>     worthwhile to have at least the self-ID-complete IRQ BH performed 
> in
>     a non-atomic context.  We should try to move as much of the
>     firewire-core self-ID-complete handler as possible out of the 
> currently
>     spinlock protected section in order make more of this stuff
>     preemptible and replace a few GFP_ATOMIC slab allocations by 
> GFP_NOFS
>     ones.  (Could be GFP_KERNEL in absence of firewire-sbp2.)
>     I would have liked to work on this already long ago, but such is 
> life.
>   - How do you propose to access the PHY registers without sleeping?
>     Or more to the point:  How do you propose to mix sleeping and
>     non-sleeping PHY register accesses?  (Since we can't get rid of
>     the sleeping ones.)  If the accesses are not fully serialized, you 
> will
>     get corrupt PHY reg reads or writes.  If they are fully serialized, 
> the
>     non-sleeping PHY reg accesses need to go a try-lock route and will 
> be
>     forced to error out during periods when a sleeping PHY reg access 
> goes
>     on, without even the ability to reschedule if it is done in a 
> tasklet
>     context.

I totally agree.

Stephan
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