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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 09 Mar 2016 10:51:06 +0100
Subject: arm: at91: do not disable/enable clocks in a row
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz
Currently the driver will disable the clock and enable it one line later
if it is switching from periodic mode into one shot.
This can be avoided and causes a needless warning on -RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/clocksource/tcb_clksrc.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -126,6 +126,7 @@ static struct clocksource clksrc = {
struct tc_clkevt_device {
struct clock_event_device clkevt;
struct clk *clk;
+ bool clk_enabled;
void __iomem *regs;
};
@@ -143,6 +144,24 @@ static struct tc_clkevt_device *to_tc_cl
*/
static u32 timer_clock;
+static void tc_clk_disable(struct clock_event_device *d)
+{
+ struct tc_clkevt_device *tcd = to_tc_clkevt(d);
+
+ clk_disable(tcd->clk);
+ tcd->clk_enabled = false;
+}
+
+static void tc_clk_enable(struct clock_event_device *d)
+{
+ struct tc_clkevt_device *tcd = to_tc_clkevt(d);
+
+ if (tcd->clk_enabled)
+ return;
+ clk_enable(tcd->clk);
+ tcd->clk_enabled = true;
+}
+
static int tc_shutdown(struct clock_event_device *d)
{
struct tc_clkevt_device *tcd = to_tc_clkevt(d);
@@ -150,8 +169,14 @@ static int tc_shutdown(struct clock_even
writel(0xff, regs + ATMEL_TC_REG(2, IDR));
writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR));
+ return 0;
+}
+
+static int tc_shutdown_clk_off(struct clock_event_device *d)
+{
+ tc_shutdown(d);
if (!clockevent_state_detached(d))
- clk_disable(tcd->clk);
+ tc_clk_disable(d);
return 0;
}
@@ -164,7 +189,7 @@ static int tc_set_oneshot(struct clock_e
if (clockevent_state_oneshot(d) || clockevent_state_periodic(d))
tc_shutdown(d);
- clk_enable(tcd->clk);
+ tc_clk_enable(d);
/* slow clock, count up to RC, then irq and stop */
writel(timer_clock | ATMEL_TC_CPCSTOP | ATMEL_TC_WAVE |
@@ -186,7 +211,7 @@ static int tc_set_periodic(struct clock_
/* By not making the gentime core emulate periodic mode on top
* of oneshot, we get lower overhead and improved accuracy.
*/
- clk_enable(tcd->clk);
+ tc_clk_enable(d);
/* slow clock, count up to RC, then irq and restart */
writel(timer_clock | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO,
@@ -220,7 +245,7 @@ static struct tc_clkevt_device clkevt =
/* Should be lower than at91rm9200's system timer */
.rating = 125,
.set_next_event = tc_next_event,
- .set_state_shutdown = tc_shutdown,
+ .set_state_shutdown = tc_shutdown_clk_off,
.set_state_periodic = tc_set_periodic,
.set_state_oneshot = tc_set_oneshot,
},
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