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Subject[PATCH V2] ARM: imx: add cpuidle support for i.mx6ul
Date
This patch enables cpuidle driver for i.MX6UL, it
reuses i.MX6SX's cpuidle driver, 3 levels of cpuidle
supported:

1. ARM WFI;
2. SOC in WAIT mode;
3. SOC in WAIT mode + ARM power off.

As i.MX6UL has cortex-A7 CORE with an internal L2
cache, so flushing it before powering down ARM platform
is necessary, flush_cache_all() in last step of cpu_suspend
has very small overhead, just call it to avoid cache
type check for different platforms.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
---
changes since V1:
remove L2 cache contional code, just call flush_cache_all
is just fine since it has very small overhead for L1 cache flush.
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 261aaa4..c5a5c3a 100644
--- a/arch/arm/mach-imx/cpuidle-imx6sx.c
+++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
@@ -9,6 +9,7 @@
#include <linux/cpuidle.h>
#include <linux/cpu_pm.h>
#include <linux/module.h>
+#include <asm/cacheflush.h>
#include <asm/cpuidle.h>
#include <asm/suspend.h>

@@ -17,6 +18,15 @@

static int imx6sx_idle_finish(unsigned long val)
{
+ /*
+ * for Cortex-A7 which has an internal L2
+ * cache, need to flush it before powering
+ * down ARM platform, since flushing L1 cache
+ * here again has very small overhead, compared
+ * to adding conditional code for L2 cache type,
+ * just call flush_cache_all() is fine.
+ */
+ flush_cache_all();
cpu_do_idle();

return 0;
diff --git a/arch/arm/mach-imx/mach-imx6ul.c b/arch/arm/mach-imx/mach-imx6ul.c
index 6bb7d9c..58a2b88 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))
platform_device_register_simple("imx6q-cpufreq", -1, NULL, 0);
}
--
1.9.1
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