[v6,2/3] ARM: rockchip: ensure CPU to enter WFI/WFE state
diff mbox

Message ID 1433843400-24831-3-git-send-email-wxt@rock-chips.com
State New
Headers show

Commit Message

Caesar Wang June 9, 2015, 9:49 a.m. UTC
The patch can ensure that v7_exit_coherency_flush() in rockchip_cpu_die()
executed in time.
The mdelay(1) has enough time to fix the problem of CPU offlining.
That's a workaround way in rockchip hotplug code,
At least, we haven't a better way to solve it. Who know,
that maybe fixed by chip (hardware) in the future.

Signed-off-by: Caesar Wang <wxt@rock-chips.com>

---

Changes in v6:
- Fix the delay 1ms describing.
Series-changes: 5
- Fix the patch decription.
- Add the changelog.
Series-changes: 2
- As Kever points out, Fix the subject typo WFI/WFE.

 arch/arm/mach-rockchip/platsmp.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Douglas Anderson June 9, 2015, 6:13 p.m. UTC | #1
Caesar,

On Tue, Jun 9, 2015 at 2:49 AM, Caesar Wang <wxt@rock-chips.com> wrote:
> The patch can ensure that v7_exit_coherency_flush() in rockchip_cpu_die()
> executed in time.
> The mdelay(1) has enough time to fix the problem of CPU offlining.
> That's a workaround way in rockchip hotplug code,
> At least, we haven't a better way to solve it. Who know,
> that maybe fixed by chip (hardware) in the future.
>
> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
>
> ---
>
> Changes in v6:
> - Fix the delay 1ms describing.
> Series-changes: 5
> - Fix the patch decription.
> - Add the changelog.
> Series-changes: 2
> - As Kever points out, Fix the subject typo WFI/WFE.
>
>  arch/arm/mach-rockchip/platsmp.c | 7 +++++++
>  1 file changed, 7 insertions(+)

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Kever Yang June 10, 2015, 5:59 a.m. UTC | #2
Hi Caesar,

On 06/09/2015 05:49 PM, Caesar Wang wrote:
> The patch can ensure that v7_exit_coherency_flush() in rockchip_cpu_die()
> executed in time.
> The mdelay(1) has enough time to fix the problem of CPU offlining.
> That's a workaround way in rockchip hotplug code,
> At least, we haven't a better way to solve it. Who know,
> that maybe fixed by chip (hardware) in the future.
>
> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
>
> ---
>
> Changes in v6:
> - Fix the delay 1ms describing.
> Series-changes: 5
> - Fix the patch decription.
> - Add the changelog.
> Series-changes: 2
> - As Kever points out, Fix the subject typo WFI/WFE.
>
>   arch/arm/mach-rockchip/platsmp.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
> index b379cc8..d629206 100644
> --- a/arch/arm/mach-rockchip/platsmp.c
> +++ b/arch/arm/mach-rockchip/platsmp.c
> @@ -322,6 +322,13 @@ static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
>   #ifdef CONFIG_HOTPLUG_CPU
>   static int rockchip_cpu_kill(unsigned int cpu)
>   {
> +	/*
> +	 * We need a delay here to ensure that the dying CPU can finish
> +	 * executing v7_coherency_exit() and reach the WFI/WFE state
> +	 * prior to having the power domain disabled.
> +	 */
> +	mdelay(1);
> +
>   	pmu_set_power_domain(0 + cpu, false);
>   	return 1;
>   }
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

Patch
diff mbox

diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
index b379cc8..d629206 100644
--- a/arch/arm/mach-rockchip/platsmp.c
+++ b/arch/arm/mach-rockchip/platsmp.c
@@ -322,6 +322,13 @@  static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
 #ifdef CONFIG_HOTPLUG_CPU
 static int rockchip_cpu_kill(unsigned int cpu)
 {
+	/*
+	 * We need a delay here to ensure that the dying CPU can finish
+	 * executing v7_coherency_exit() and reach the WFI/WFE state
+	 * prior to having the power domain disabled.
+	 */
+	mdelay(1);
+
 	pmu_set_power_domain(0 + cpu, false);
 	return 1;
 }