[PATCH] ARM: mxs: Setup scheduler clock
From: Shawn Guo <hidden>
Date: 2012-11-12 01:54:21
Also in:
linux-rt-users
On Thu, Nov 08, 2012 at 11:45:45PM +0100, Stanislav Meduna wrote:
Hi,
OK, as the problem with 16-bit fast ticking timer looks to
be more complicated, I'd like to submit the patch for the 32-bit
ones.
Thanks
--
StanoFrom 74092cc0217a5bab6f80ee07aa188a54f5792634 Mon Sep 17 00:00:00 2001 From: Stanislav Meduna <redacted> Date: Mon, 8 Nov 2012 23:39:14 +0100 Subject: [PATCH] ARM: mxs: Setup scheduler clock Setup scheduler clock on ARM MXS platforms with a 32-bit timrot such as MX.28. This allows the scheduler to use sub-jiffy resolution.
s/MX.28/i.MX28 I fixed it up and applied the patch. Thanks. Shawn
quoted hunk ↗ jump to hunk
The corresponding change for 16-bit v1 timrots is not possible at the moment due to rounding issues with clock values wrapping faster than once per several seconds in the common ARM platform code. Signed-off-by: Stanislav Meduna <redacted> --- arch/arm/mach-mxs/timer.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-)diff --git a/arch/arm/mach-mxs/timer.c b/arch/arm/mach-mxs/timer.c index 564a632..4b6e36c 100644 --- a/arch/arm/mach-mxs/timer.c +++ b/arch/arm/mach-mxs/timer.c@@ -26,6 +26,7 @@ #include <linux/clk.h> #include <asm/mach/time.h> +#include <asm/sched_clock.h> #include <mach/mxs.h> #include <mach/common.h>@@ -230,15 +231,22 @@ static struct clocksource clocksource_mxs = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static u32 notrace mxs_read_sched_clock_v2(void) +{ + return ~readl_relaxed(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1)); +} + static int __init mxs_clocksource_init(struct clk *timer_clk) { unsigned int c = clk_get_rate(timer_clk); if (timrot_is_v1()) clocksource_register_hz(&clocksource_mxs, c); - else + else { clocksource_mmio_init(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1), "mxs_timer", c, 200, 32, clocksource_mmio_readl_down); + setup_sched_clock(mxs_read_sched_clock_v2, 32, c); + } return 0; }-- 1.7.0.4