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Date: Tue, 6 Mar 2012 10:38:05 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Clemens Ladisch <clemens@ladisch.de>
Cc: Thomas Gleixner <tglx@linutronix.de>, maglyx@gmail.com,
        Arnd Bergmann <arnd@arndb.de>, John Stultz <johnstul@us.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch 4/4] hpet: factor timer allocate from open
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On Tue, 06 Mar 2012 16:04:21 +0100
Clemens Ladisch <clemens@ladisch.de> wrote:

> Thomas Gleixner wrote:
> > On Mon, 5 Mar 2012, akpm@linux-foundation.org wrote:
> >> From: Magnus Lynch <maglyx@gmail.com>
> >> Subject: hpet: factor timer allocate from open
> >>
> >> The current implementation of the /dev/hpet driver couples opening the
> >> device with allocating one of the (scarce) timers (aka comparators).  This
> >> is a limitation in that the main counter may be valuable to applications
> >> seeking a high-resolution timer who have no use for the interrupt
> >> generating functionality of the comparators.
> >>
> >> This patch alters the open semantics so that when the device is opened, no
> >> timer is allocated.  Operations that depend on a timer being in context
> >> implicitly attempt allocating a timer, to maintain backward compatibility.
> >
> > AFAICT, there is only fasync which calls hpet_alloc_timer(). All other
> > functions are broken by this chage.
> 
> Indeed.  There was another call in hpet_ioctl_common(), but it appears
> that one somehow got dropped.
> 
> Magnus, is this the patch that you submitted and have tested?

I've been carrying this patch since March 2010 - perhaps it rotted.