[GIT PULL] clocksource fixes for 4.19-rc

[GIT PULL] clocksource fixes for 4.19-rc

[Daniel Lezcano]

Thomas, Ingo,

This pull request for clockevents / clocksource contains two fixes and
is based on tip/timers/urgent:

 - Add the CLOCK_SOURCE_SUSPEND_NONSTOP for non-am43 SoCs (Keerthy)

 - Fix set_next_event handler for the fttmr010 (Tao Ren)


Thanks !

  -- Daniel


The following changes since commit e2c631ba75a7e727e8db0a9d30a06bfd434adb3a:

  clocksource: Revert "Remove kthread" (2018-09-06 23:38:35 +0200)

are available in the git repository at:

  https://git.linaro.org/people/daniel.lezcano/linux.git
clockevents/4.19-fixes

for you to fetch changes up to 4451d3f59f2a6f95e5d205c2d04ea072955d080d:

  clocksource/drivers/fttmr010: Fix set_next_event handler (2018-09-24
06:13:31 +0200)

----------------------------------------------------------------
Keerthy (1):
      clocksource/drivers/ti-32k: Add CLOCK_SOURCE_SUSPEND_NONSTOP flag
for non-am43 SoCs

Tao Ren (1):
      clocksource/drivers/fttmr010: Fix set_next_event handler

 drivers/clocksource/timer-fttmr010.c | 18 +++++++++++-------
 drivers/clocksource/timer-ti-32k.c   |  3 +++
 2 files changed, 14 insertions(+), 7 deletions(-)




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[PATCH 1/2] clocksource/drivers/ti-32k: Add CLOCK_SOURCE_SUSPEND_NONSTOP flag for non-am43 SoCs

[Daniel Lezcano]

From: Keerthy <j-keerthy@ti.com>

The 32k clocksource is NONSTOP for non-am43 SoCs. Hence
add the flag for all the other SoCs.

Reported-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/timer-ti-32k.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/clocksource/timer-ti-32k.c b/drivers/clocksource/timer-ti-32k.c
index 29e2e1a..6949a91 100644
--- a/drivers/clocksource/timer-ti-32k.c
+++ b/drivers/clocksource/timer-ti-32k.c
@@ -97,6 +97,9 @@ static int __init ti_32k_timer_init(struct device_node *np)
 		return -ENXIO;
 	}
 
+	if (!of_machine_is_compatible("ti,am43"))
+		ti_32k_timer.cs.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP;
+
 	ti_32k_timer.counter = ti_32k_timer.base;
 
 	/*
-- 
2.7.4

[PATCH 2/2] clocksource/drivers/fttmr010: Fix set_next_event handler

[Daniel Lezcano]

From: Tao Ren <taoren@fb.com>

Currently, the aspeed MATCH1 register is updated to <current_count -
cycles> in set_next_event handler, with the assumption that COUNT
register value is preserved when the timer is disabled and it continues
decrementing after the timer is enabled. But the assumption is wrong:
RELOAD register is loaded into COUNT register when the aspeed timer is
enabled, which means the next event may be delayed because timer
interrupt won't be generated until <0xFFFFFFFF - current_count +
cycles>.

The problem can be fixed by updating RELOAD register to <cycles>, and
COUNT register will be re-loaded when the timer is enabled and interrupt
is generated when COUNT register overflows.

The test result on Facebook Backpack-CMM BMC hardware (AST2500) shows
the issue is fixed: without the patch, usleep(100) suspends the process
for several milliseconds (and sometimes even over 40 milliseconds);
after applying the fix, usleep(100) takes averagely 240 microseconds to
return under the same workload level.

Signed-off-by: Tao Ren <taoren@fb.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Lei YU <mine260309@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/timer-fttmr010.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/timer-fttmr010.c b/drivers/clocksource/timer-fttmr010.c
index c020038..cf93f64 100644
--- a/drivers/clocksource/timer-fttmr010.c
+++ b/drivers/clocksource/timer-fttmr010.c
@@ -130,13 +130,17 @@ static int fttmr010_timer_set_next_event(unsigned long cycles,
 	cr &= ~fttmr010->t1_enable_val;
 	writel(cr, fttmr010->base + TIMER_CR);
 
-	/* Setup the match register forward/backward in time */
-	cr = readl(fttmr010->base + TIMER1_COUNT);
-	if (fttmr010->count_down)
-		cr -= cycles;
-	else
-		cr += cycles;
-	writel(cr, fttmr010->base + TIMER1_MATCH1);
+	if (fttmr010->count_down) {
+		/*
+		 * ASPEED Timer Controller will load TIMER1_LOAD register
+		 * into TIMER1_COUNT register when the timer is re-enabled.
+		 */
+		writel(cycles, fttmr010->base + TIMER1_LOAD);
+	} else {
+		/* Setup the match register forward in time */
+		cr = readl(fttmr010->base + TIMER1_COUNT);
+		writel(cr + cycles, fttmr010->base + TIMER1_MATCH1);
+	}
 
 	/* Start */
 	cr = readl(fttmr010->base + TIMER_CR);
-- 
2.7.4