linux-kernel - [PATCH] clocksource/imx: allow timer irq affinity change

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Date:	Wed, 14 Oct 2015 11:24:17 +0200
From:	Lucas Stach <l.stach@...gutronix.de>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	Shawn Guo <shawnguo@...nel.org>, kernel@...gutronix.de,
	patchwork-lst@...gutronix.de, linux-kernel@...r.kernel.org
Subject: [PATCH] clocksource/imx: allow timer irq affinity change

Allow the timer core to change the smp affinity of the broadcast timer
irq by setting CLOCK_EVT_FEAT_DYNIRQ flag. For this to work the timer
core needs to be told about the used irq.

This reduces interrupt pressure and wakeups on CPU0 as well as vastly
reducing the number of timer broadcast IPIs.

Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
---
 drivers/clocksource/timer-imx-gpt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-imx-gpt.c b/drivers/clocksource/timer-imx-gpt.c
index 839aba92fc39..99ec96769dda 100644
--- a/drivers/clocksource/timer-imx-gpt.c
+++ b/drivers/clocksource/timer-imx-gpt.c
@@ -305,13 +305,14 @@ static int __init mxc_clockevent_init(struct imx_timer *imxtm)
 	struct irqaction *act = &imxtm->act;
 
 	ced->name = "mxc_timer1";
-	ced->features = CLOCK_EVT_FEAT_ONESHOT;
+	ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
 	ced->set_state_shutdown = mxc_shutdown;
 	ced->set_state_oneshot = mxc_set_oneshot;
 	ced->tick_resume = mxc_shutdown;
 	ced->set_next_event = imxtm->gpt->set_next_event;
 	ced->rating = 200;
 	ced->cpumask = cpumask_of(0);
+	ced->irq = imxtm->irq;
 	clockevents_config_and_register(ced, clk_get_rate(imxtm->clk_per),
 					0xff, 0xfffffffe);
 
-- 
2.6.1

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