From mboxrd@z Thu Jan 1 00:00:00 1970 From: kever.yang@rock-chips.com (Kever Yang) Date: Wed, 10 Jun 2015 13:59:16 +0800 Subject: [PATCH v6 2/3] ARM: rockchip: ensure CPU to enter WFI/WFE state In-Reply-To: <1433843400-24831-3-git-send-email-wxt@rock-chips.com> References: <1433843400-24831-1-git-send-email-wxt@rock-chips.com> <1433843400-24831-3-git-send-email-wxt@rock-chips.com> Message-ID: <5577D234.5000502@rock-chips.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > > --- > > 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