Re: [patch 4/4] hpet: factor timer allocate from open

[Thomas Gleixner]

On Mon, 5 Mar 2012, akpm@xxxxxxxxxxxxxxxxxxxx wrote:

> From: Magnus Lynch <maglyx@xxxxxxxxx>
> 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.

>  There is also an IOCTL (HPET_ALLOC_TIMER _IO) added so that the
> allocation may be done explicitly.  (I prefer the explicit open then

And that IOCTL does what? Return 0 is not really useful functionality.

Thanks,

	tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/