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[16/17] clocksource/drivers/mips-gic-timer: Add fastpath for local timer updates

Message ID 1509312035-17368-16-git-send-email-daniel.lezcano@linaro.org
State Accepted
Commit f16ff2bdb135e2eb35488264006b575c476ea597
Headers show
Series [01/17] dt-bindings: timer: renesas, cmt: Fix SoC-specific compatible values | expand

Commit Message

Daniel Lezcano Oct. 29, 2017, 9:20 p.m. UTC 
From: Matt Redfearn <matt.redfearn@mips.com>


Always accessing the compare register via the CM redirect region is
(relatively) slow. If the timer being updated is the current CPUs
then this can be shortcutted by writing to the CM VP local region.

Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

---
 drivers/clocksource/mips-gic-timer.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

-- 
2.7.4
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Patch

diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
index 775dea0..a04808a 100644
--- a/drivers/clocksource/mips-gic-timer.c
+++ b/drivers/clocksource/mips-gic-timer.c
@@ -39,13 +39,18 @@  static u64 notrace gic_read_count(void)
 
 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
 {
+	int cpu = cpumask_first(evt->cpumask);
 	u64 cnt;
 	int res;
 
 	cnt = gic_read_count();
 	cnt += (u64)delta;
-	write_gic_vl_other(mips_cm_vp_id(cpumask_first(evt->cpumask)));
-	write_gic_vo_compare(cnt);
+	if (cpu == raw_smp_processor_id()) {
+		write_gic_vl_compare(cnt);
+	} else {
+		write_gic_vl_other(mips_cm_vp_id(cpu));
+		write_gic_vo_compare(cnt);
+	}
 	res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
 	return res;
 }