Subject: Re: [PATCH] For test only: pmac_zilog fixes (cups lockup at boot):
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: "debian-powerpc@lists.debian.org" <debian-powerpc@lists.debian.org>,
       Linux Kernel list <linux-kernel@vger.kernel.org>,
       Matthias Urlichs <smurf@smurf.noris.de>,
       =?ISO-8859-1?Q?Martin-=C9ric?= Racine <q-funk@pp.fishpool.fi>
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Date: Fri, 05 Mar 2004 22:14:47 +1100
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On Fri, 2004-03-05 at 20:48, Russell King wrote:
> On Fri, Mar 05, 2004 at 08:29:12PM +1100, Benjamin Herrenschmidt wrote:
> > 
> > > Yes, I know - but the point is its impossible to review, and I think
> > > you at least have an extra level of locking which isn't needed.
> > > 
> > > But I wouldn't know because of the huge number of changes which make
> > > it impossible to read.
> > 
> > That semaphore locking is only used to guard open/close against the
> > power management callback. It greatly simplify the deal with the shared
> > irq (the irq is shared between both ports). It's not used during
> > normal operations.
> 
> Err.  What power management callback?  Are you not using uart_suspend_port
> and uart_resume_port?
>
> These functions do all the locking for you already - using state->sem.

Well... I could, but I have additional crap related to shutting
the SCC down. I need to disable_irq() at the irq controller level
after both ports have been shut down only, since a down SCC would
leave a dangling irq line...

> Like I said, I can't see the twigs for the forest due to the shear
> noise caused by the up -> uap change.

Yah, I know. Difficult to split though. I'd suggest you just look
at the driver as a whole after the patch is applied ;)

Ben.


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