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Date: Wed, 24 Jan 2018 09:35:05 +0800 From: Peng Fan <van.freenix@...il.com> To: Peng Fan <peng.fan@....com> Cc: shawnguo@...nel.org, kernel@...gutronix.de, fabio.estevam@....com, aisheng.dong@....com, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/2] ARM: imx: cpuidle-imx6q: configure CCM to RUN mode when CPU is active Hi, For the two patch, ping.. On Sat, Dec 30, 2017 at 09:53:19PM +0800, Peng Fan wrote: >There are two states in i.MX6Q cpuidle driver. >state[1]: ARM WFI mode >state[2]: i.MX6Q WAIT mode > >Take i.MX6DL as example, think out such a case: >1. CPU0/1 both run at normal mode >2. On CPU0, `sleep 1` is executed. And there are no workload on CPU1. >3. CPU0 first runs into state[2] and 'wfi' instruction. Switched to use > GPT broadcast. >4. CPU1 runs into state[2] and configure CCM to WAIT MODE, > then 'wfi' instruction. Now arm_clk and local timer clock are > shutdown. Switched to use GPT broadcast >5. GPT broadcast timer interrupt comes to GPC/GIC, then CPU0 wakes up. > CPU0 switched to use arm local timer. CPU1 is still sleeping. >6. No workload on CPU0, CPU0 runs into state[1]. But CCM register > is still not restored to Normal RUN mode. 'wfi' + CCM WAIT will > cause arm_clk and arm core clk. > Now CPU0 stops, which is not correct. > >So, need to make sure CCM configured to RUN mode when any cpu exit >state[2]. > >In this patch, >When CPU exits state[2], it configures CCM to RUN mode. >When all CPUs enters state[2], the last CPU needs to check >whether it's ok to configure CCM to WAIT mode or not. > >Signed-off-by: Peng Fan <peng.fan@....com> >--- > >V1: > This is to upstream patch: > http://git.freescale.com/git/cgit.cgi/imx/linux-imx.git/commit/?h=imx_4.9.11_1.0.0_ga&id=0d980646ee068b92db71fd5e4e4efcbc33749cbd > > arch/arm/mach-imx/cpuidle-imx6q.c | 3 +++ > 1 file changed, 3 insertions(+) > >diff --git a/arch/arm/mach-imx/cpuidle-imx6q.c b/arch/arm/mach-imx/cpuidle-imx6q.c >index bfeb25aaf9a2..4d342e2fdfe6 100644 >--- a/arch/arm/mach-imx/cpuidle-imx6q.c >+++ b/arch/arm/mach-imx/cpuidle-imx6q.c >@@ -30,6 +30,8 @@ static int imx6q_enter_wait(struct cpuidle_device *dev, > if (!spin_trylock(&master_lock)) > goto idle; > imx6_set_lpm(WAIT_UNCLOCKED); >+ if (atomic_read(&master) != num_online_cpus()) >+ imx6_set_lpm(WAIT_CLOCKED); > cpu_do_idle(); > imx6_set_lpm(WAIT_CLOCKED); > spin_unlock(&master_lock); >@@ -41,6 +43,7 @@ static int imx6q_enter_wait(struct cpuidle_device *dev, > done: > atomic_dec(&master); > >+ imx6_set_lpm(WAIT_CLOCKED); > return index; > } > >-- >2.14.1 > Thanks, Peng. --
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