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
> --
> Stano
>
> From 74092cc0217a5bab6f80ee07aa188a54f5792634 Mon Sep 17 00:00:00 2001
> From: Stanislav Meduna <stano@xxxxxxxxxx>
> 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
> 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 <stano@xxxxxxxxxx>
> ---
> 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
>
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