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SubjectRe: [PATCH] mfd: speedup twl4030 irq response time and decrease irq disable time
Hi Tom,

On Wed, Sep 22, 2010 at 09:49:31AM +0800, tom.leiming@gmail.com wrote:
> From: Ming Lei <tom.leiming@gmail.com>
>
> This patch sets scheduler policy of twl4030 irq thread
> (twl4030_irq_thread) as SCHED_FIFO to speedup irq response
> time, just like taken by kernel threaded irq in irq_thread
> (kernel/irq/manage.c). Also higher priority than that of
> threaded irq is taken to avoid preemption from twl4030
> subchips's threaded irq handler, so pih irq disable time may
> be decreased.
Wouldn't converting your twl4030_irq_thread() to the threaded IRQ framework
fix that problem ?


> The pih irq is disabled in handle_twl4030_pih which may
> wakeup twl4030 irq thread, and the pih irq will be enabled
> again until complete of all sih irqs' handling in twl4030
> irq thread.
>
> Also for each one interrupt line of twl4030 subchip, only
> two irq events can be buffered by twl4030(4.4.2.3 of TPS65950 TRM).
Could you explain how is that related to the patch below ?

Cheers,
Samuel.



> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Cc: Balaji T K <balajitk@ti.com>
> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> Cc: linux-kernel@vger.kernel.org
> ---
> drivers/mfd/twl4030-irq.c | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
> index 097f24d..d1e0d80 100644
> --- a/drivers/mfd/twl4030-irq.c
> +++ b/drivers/mfd/twl4030-irq.c
> @@ -286,8 +286,16 @@ static int twl4030_irq_thread(void *data)
> long irq = (long)data;
> static unsigned i2c_errors;
> static const unsigned max_i2c_errors = 100;
> -
> -
> + struct sched_param param = {
> + .sched_priority = MAX_USER_RT_PRIO/2 + 10,
> + };
> +
> + /* Take higher priority than threaded irq to make us immune of
> + * preemption from twl4030 subchips's threaded irq handler, then
> + * we can complete all SIH irqs' handling and enable PIH irq
> + * again asap.
> + * */
> + sched_setscheduler(current, SCHED_FIFO, &param);
> current->flags |= PF_NOFREEZE;
>
> while (!kthread_should_stop()) {
> --
> 1.6.2.5
>

--
Intel Open Source Technology Centre
http://oss.intel.com/


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