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    SubjectRE: [PATCH] ARM: imx: add cpuidle support for i.mx6ul
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    Best Regards!
    Anson Huang



    > -----Original Message-----
    > From: Peter Chen [mailto:hzpeterchen@gmail.com]
    > Sent: 2016-08-25 3:09 PM
    > To: Yongcai Huang <anson.huang@nxp.com>
    > Cc: linux-arm-kernel@lists.infradead.org; lkml <linux-kernel@vger.kernel.org>;
    > Fabio Estevam <fabio.estevam@nxp.com>; shawnguo@kernel.org;
    > linux@armlinux.org.uk; kernel@pengutronix.de
    > Subject: Re: [PATCH] ARM: imx: add cpuidle support for i.mx6ul
    >
    > >
    > > Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
    > > ---
    > > arch/arm/mach-imx/cpuidle-imx6sx.c | 10 ++++++++++
    > > arch/arm/mach-imx/mach-imx6ul.c | 3 +++
    > > 2 files changed, 13 insertions(+)
    > >
    > > diff --git a/arch/arm/mach-imx/cpuidle-imx6sx.c
    > > b/arch/arm/mach-imx/cpuidle-imx6sx.c
    > > index 41cdce6..b4fcc8ae 100644
    > > --- a/arch/arm/mach-imx/cpuidle-imx6sx.c
    > > +++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
    > > @@ -9,14 +9,21 @@
    > > #include <linux/cpuidle.h>
    > > #include <linux/cpu_pm.h>
    > > #include <linux/module.h>
    > > +#include <linux/of.h>
    > > +#include <asm/cacheflush.h>
    > > #include <asm/cpuidle.h>
    > > #include <asm/suspend.h>
    > >
    > > #include "common.h"
    > > #include "cpuidle.h"
    > >
    > > +static bool pl310_available;
    > > +
    >
    >
    > > static int imx6sx_idle_finish(unsigned long val) {
    > > + /* check if need to flush internal L2 cache */
    > > + if (!pl310_available)
    >
    > Just wondering why you need an extra variable here?
    > Calling of_find_compatible_node takes long time at that time?
    >
    > Peter
    >

    Because cpu idle enter/exit is called very frequently, so calling
    of_find_compatible_node in every cpu idle thread is adding too
    many latency, I think adding a variable is better.

    Anson

    > > + flush_cache_all();
    > > cpu_do_idle();
    > >
    > > return 0;
    > > @@ -101,5 +108,8 @@ int __init imx6sx_cpuidle_init(void)
    > > imx_gpc_set_arm_power_up_timing(2, 1);
    > > imx_gpc_set_arm_power_down_timing(1, 1);
    > >
    > > + if (of_find_compatible_node(NULL, NULL, "arm,pl310-cache"))
    > > + pl310_available = true;
    > > +
    > > return cpuidle_register(&imx6sx_cpuidle_driver, NULL); } diff
    > > --git a/arch/arm/mach-imx/mach-imx6ul.c
    > > b/arch/arm/mach-imx/mach-imx6ul.c index c2cd61c..9c5e8f3 100644
    > > --- a/arch/arm/mach-imx/mach-imx6ul.c
    > > +++ b/arch/arm/mach-imx/mach-imx6ul.c
    > > @@ -16,6 +16,7 @@
    > > #include <asm/mach/map.h>
    > >
    > > #include "common.h"
    > > +#include "cpuidle.h"
    > >
    > > static void __init imx6ul_enet_clk_init(void) { @@ -80,6 +81,8 @@
    > > static void __init imx6ul_init_irq(void)
    > >
    > > static void __init imx6ul_init_late(void) {
    > > + imx6sx_cpuidle_init();
    > > +
    > > if (IS_ENABLED(CONFIG_ARM_IMX6Q_CPUFREQ)) {
    > > imx6_pm_opp_init();
    > > platform_device_register_simple("imx6q-cpufreq", -1,
    > > NULL, 0);
    > > --
    > > 1.9.1
    > >
    > >
    > > _______________________________________________
    > > linux-arm-kernel mailing list
    > > linux-arm-kernel@lists.infradead.org
    > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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