2017-03-09 16:58:53

by Romain Izard

Subject: [PATCH v1] Revert "clocksource/drivers/tcb_clksrc: Use 32 bit tcb as sched_clock"

This reverts commit 7b9f1d16e6d1 ("clocksource/drivers/tcb_clksrc: Use
32 bit tcb as sched_clock"). In the current state, the kernel warns
against a late registration of the new sched_clock, the printk clock
resets after only a few minutes, and it seems that scheduling can be
affected as well.

Signed-off-by: Romain Izard <[email protected]>
---
drivers/clocksource/tcb_clksrc.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index 745844ee973e..d4ca9962a759 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -10,7 +10,6 @@
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/atmel_tc.h>
-#include <linux/sched_clock.h>


/*
@@ -57,14 +56,9 @@ static u64 tc_get_cycles(struct clocksource *cs)
return (upper << 16) | lower;
}

-static u32 tc_get_cv32(void)
-{
- return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV));
-}
-
static u64 tc_get_cycles32(struct clocksource *cs)
{
- return tc_get_cv32();
+ return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV));
}

static struct clocksource clksrc = {
@@ -75,11 +69,6 @@ static struct clocksource clksrc = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};

-static u64 notrace tc_read_sched_clock(void)
-{
- return tc_get_cv32();
-}
-
#ifdef CONFIG_GENERIC_CLOCKEVENTS

struct tc_clkevt_device {
@@ -350,9 +339,6 @@ static int __init tcb_clksrc_init(void)
clksrc.read = tc_get_cycles32;
/* setup ony channel 0 */
tcb_setup_single_chan(tc, best_divisor_idx);
-
- /* register sched_clock on chips with single 32 bit counter */
- sched_clock_register(tc_read_sched_clock, 32, divided_rate);
} else {
/* tclib will give us three clocks no matter what the
* underlying platform supports.
--
2.9.3

2017-03-11 21:30:25

by Daniel Lezcano

Subject: Re: [PATCH v1] Revert "clocksource/drivers/tcb_clksrc: Use 32 bit tcb as sched_clock"

On Thu, Mar 09, 2017 at 05:58:38PM +0100, Romain Izard wrote:
> This reverts commit 7b9f1d16e6d1 ("clocksource/drivers/tcb_clksrc: Use
> 32 bit tcb as sched_clock"). In the current state, the kernel warns
> against a late registration of the new sched_clock, the printk clock
> resets after only a few minutes, and it seems that scheduling can be
> affected as well.
>
> Signed-off-by: Romain Izard <[email protected]>
> ---

Applied, thanks.

-- Daniel