linux-kernel - [PATCH v2 5/9] clocksource/cadence_ttc: Adjust interval in clock notifier

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Message-Id: <1385514296-26702-6-git-send-email-soren.brinkmann@xilinx.com>
Date:	Tue, 26 Nov 2013 17:04:52 -0800
From:	Soren Brinkmann <soren.brinkmann@...inx.com>
To:	Rob Herring <rob.herring@...xeda.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Russell King <linux@....linux.org.uk>,
	Michal Simek <michal.simek@...inx.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org,
	Soren Brinkmann <soren.brinkmann@...inx.com>
Subject: [PATCH v2 5/9] clocksource/cadence_ttc: Adjust interval in clock notifier

The clockevent has to be reprogrammed if the timer's input
clock frequency changes and the timer is in periodic mode, in order to
maintain the correct timer interval.

Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
---
v2:
 - adjust the timer interval while the timer interrupt is disabled
---
 drivers/clocksource/cadence_ttc_timer.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index 246d018d1e63..77517675653e 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -322,6 +322,9 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
 	switch (event) {
 	case POST_RATE_CHANGE:
 	{
+		/* update cached frequency */
+		ttc->freq = ndata->new_rate;
+
 		/*
 		 * clockevents_update_freq should be called with IRQ disabled on
 		 * the CPU the timer provides events for. The timer we use is
@@ -329,12 +332,15 @@ static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
 		 * cores.
 		 */
 		disable_irq(ttcce->ce.irq);
+
 		clockevents_update_freq(&ttcce->ce,
 				ndata->new_rate / PRESCALE);
-		enable_irq(ttcce->ce.irq);
 
-		/* update cached frequency */
-		ttc->freq = ndata->new_rate;
+		if (ttcce->ce.mode == CLOCK_EVT_MODE_PERIODIC)
+			ttc_set_interval(ttc, DIV_ROUND_CLOSEST(ttc->freq,
+						PRESCALE * HZ));
+
+		enable_irq(ttcce->ce.irq);
 
 		/* fall through */
 	}
-- 
1.8.4.4

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