[PATCH] ARM: imx6: initialize CCM_CLPCR_LPM into RUN mode earlier
Tyler Baker
tyler.baker at linaro.org
Wed Apr 29 13:43:39 PDT 2015
On 28 April 2015 at 22:58, Shawn Guo <shawn.guo at linaro.org> wrote:
> Commit 4631960d26da ("ARM: imx6: set initial power mode in pm function")
> moves imx6_set_lpm() from clock init function into
> imx6_pm_common_init(). This causes a hang when cpuidle support is
> enabled. The reason for that is ARM core clock is shut down
> unexpectedly by WAIT mode. It happens with the following call stack:
>
> cpuidle_register_governor()
> cpuidle_switch_governor()
> cpuidle_uninstall_idle_handler()
> synchronize_sched()
> wait_rcu_gp()
> wait_for_completion()
>
> When wait_for_completion() is called as above, all cores are idle/WFI.
> Hence, the reset value of CCM_CLPCR_LPM - WAIT mode, will trigger a
> hardware shutdown of the ARM core clock.
>
> To fix the regression, we need to ensure that CCM_CLPCR_LPM is
> initialized into RUN mode earlier than cpuidle governor registration,
> which is a postcore_initcall. This patch creates function
> imx6_pm_ccm_init() to map CCM block and initialize CCM_CLPCR_LPM into
> RUN mode, and have the function called from machine .init_irq hook,
> which should be early enough.
>
> Reported-by: Kevin Hilman <khilman at kernel.org>
> Fixes: 4631960d26da ("ARM: imx6: set initial power mode in pm function")
> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
Tested-by: Tyler Baker <tyler.baker at linaro.org>
I have applied this patch on top of next-20150429[1] and build/boot
tested it with the kernelci.org farm. With these results[2], I can
confirm the IMX6 boot regression reported is fixed by this patch.
> ---
> arch/arm/mach-imx/common.h | 1 +
> arch/arm/mach-imx/mach-imx6q.c | 1 +
> arch/arm/mach-imx/mach-imx6sl.c | 1 +
> arch/arm/mach-imx/mach-imx6sx.c | 1 +
> arch/arm/mach-imx/pm-imx6.c | 28 ++++++++++++++++++----------
> 5 files changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h
> index d1e2873f807e..fbd86f1b7f3b 100644
> --- a/arch/arm/mach-imx/common.h
> +++ b/arch/arm/mach-imx/common.h
> @@ -123,6 +123,7 @@ static inline void v7_cpu_resume(void) {}
> static inline void imx6_suspend(void __iomem *ocram_vbase) {}
> #endif
>
> +void imx6_pm_ccm_init(const char *ccm_compat);
> void imx6q_pm_init(void);
> void imx6dl_pm_init(void);
> void imx6sl_pm_init(void);
> diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
> index 3ab61549ce0f..9602cc12d2f1 100644
> --- a/arch/arm/mach-imx/mach-imx6q.c
> +++ b/arch/arm/mach-imx/mach-imx6q.c
> @@ -393,6 +393,7 @@ static void __init imx6q_init_irq(void)
> imx_init_l2cache();
> imx_src_init();
> irqchip_init();
> + imx6_pm_ccm_init("fsl,imx6q-ccm");
> }
>
> static const char * const imx6q_dt_compat[] __initconst = {
> diff --git a/arch/arm/mach-imx/mach-imx6sl.c b/arch/arm/mach-imx/mach-imx6sl.c
> index 12a1b098fc6a..300326373166 100644
> --- a/arch/arm/mach-imx/mach-imx6sl.c
> +++ b/arch/arm/mach-imx/mach-imx6sl.c
> @@ -66,6 +66,7 @@ static void __init imx6sl_init_irq(void)
> imx_init_l2cache();
> imx_src_init();
> irqchip_init();
> + imx6_pm_ccm_init("fsl,imx6sl-ccm");
> }
>
> static const char * const imx6sl_dt_compat[] __initconst = {
> diff --git a/arch/arm/mach-imx/mach-imx6sx.c b/arch/arm/mach-imx/mach-imx6sx.c
> index f17b7004c24b..6a0b0614de29 100644
> --- a/arch/arm/mach-imx/mach-imx6sx.c
> +++ b/arch/arm/mach-imx/mach-imx6sx.c
> @@ -86,6 +86,7 @@ static void __init imx6sx_init_irq(void)
> imx_init_l2cache();
> imx_src_init();
> irqchip_init();
> + imx6_pm_ccm_init("fsl,imx6sx-ccm");
> }
>
> static void __init imx6sx_init_late(void)
> diff --git a/arch/arm/mach-imx/pm-imx6.c b/arch/arm/mach-imx/pm-imx6.c
> index 27bc80dab2d8..b01650d94f91 100644
> --- a/arch/arm/mach-imx/pm-imx6.c
> +++ b/arch/arm/mach-imx/pm-imx6.c
> @@ -89,7 +89,6 @@ struct imx6_pm_base {
>
> struct imx6_pm_socdata {
> u32 ddr_type;
> - const char *ccm_compat;
> const char *mmdc_compat;
> const char *src_compat;
> const char *iomuxc_compat;
> @@ -139,7 +138,6 @@ static const u32 imx6sx_mmdc_io_offset[] __initconst = {
> };
>
> static const struct imx6_pm_socdata imx6q_pm_data __initconst = {
> - .ccm_compat = "fsl,imx6q-ccm",
> .mmdc_compat = "fsl,imx6q-mmdc",
> .src_compat = "fsl,imx6q-src",
> .iomuxc_compat = "fsl,imx6q-iomuxc",
> @@ -149,7 +147,6 @@ static const struct imx6_pm_socdata imx6q_pm_data __initconst = {
> };
>
> static const struct imx6_pm_socdata imx6dl_pm_data __initconst = {
> - .ccm_compat = "fsl,imx6q-ccm",
> .mmdc_compat = "fsl,imx6q-mmdc",
> .src_compat = "fsl,imx6q-src",
> .iomuxc_compat = "fsl,imx6dl-iomuxc",
> @@ -159,7 +156,6 @@ static const struct imx6_pm_socdata imx6dl_pm_data __initconst = {
> };
>
> static const struct imx6_pm_socdata imx6sl_pm_data __initconst = {
> - .ccm_compat = "fsl,imx6sl-ccm",
> .mmdc_compat = "fsl,imx6sl-mmdc",
> .src_compat = "fsl,imx6sl-src",
> .iomuxc_compat = "fsl,imx6sl-iomuxc",
> @@ -169,7 +165,6 @@ static const struct imx6_pm_socdata imx6sl_pm_data __initconst = {
> };
>
> static const struct imx6_pm_socdata imx6sx_pm_data __initconst = {
> - .ccm_compat = "fsl,imx6sx-ccm",
> .mmdc_compat = "fsl,imx6sx-mmdc",
> .src_compat = "fsl,imx6sx-src",
> .iomuxc_compat = "fsl,imx6sx-iomuxc",
> @@ -553,16 +548,11 @@ put_node:
> static void __init imx6_pm_common_init(const struct imx6_pm_socdata
> *socdata)
> {
> - struct device_node *np;
> struct regmap *gpr;
> int ret;
>
> - np = of_find_compatible_node(NULL, NULL, socdata->ccm_compat);
> - ccm_base = of_iomap(np, 0);
> WARN_ON(!ccm_base);
>
> - imx6_set_lpm(WAIT_CLOCKED);
> -
> if (IS_ENABLED(CONFIG_SUSPEND)) {
> ret = imx6q_suspend_init(socdata);
> if (ret)
> @@ -583,6 +573,24 @@ static void __init imx6_pm_common_init(const struct imx6_pm_socdata
> IMX6Q_GPR1_GINT);
> }
>
> +void __init imx6_pm_ccm_init(const char *ccm_compat)
> +{
> + struct device_node *np;
> + u32 val;
> +
> + np = of_find_compatible_node(NULL, NULL, ccm_compat);
> + ccm_base = of_iomap(np, 0);
> + BUG_ON(!ccm_base);
> +
> + /*
> + * Initialize CCM_CLPCR_LPM into RUN mode to avoid ARM core
> + * clock being shut down unexpectedly by WAIT mode.
> + */
> + val = readl_relaxed(ccm_base + CLPCR);
> + val &= ~BM_CLPCR_LPM;
> + writel_relaxed(val, ccm_base + CLPCR);
> +}
> +
> void __init imx6q_pm_init(void)
> {
> imx6_pm_common_init(&imx6q_pm_data);
> --
> 1.9.1
>
>
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Tyler
[1] https://github.com/EmbeddedAndroid/linux/commits/to-build
[2] http://kernelci.org/boot/all/job/tbaker/kernel/v4.1-rc1-1408-g21b224526cfd/
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