| Message ID | Yqcv6crSNKuSWoTu@atomide.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
On Mon, Jun 13, 2022 at 03:39:05PM +0300, Tony Lindgren wrote: > OMAP4 uses full SoC suspend modes as idle states, as such it needs the > whole power-domain and clock-domain code from the idle path. > > All that code is not suitable to run with RCU disabled, as such push > RCU-idle deeper still. > > Signed-off-by: Tony Lindgren <tony@atomide.com> > --- > > Peter here's one more for your series, looks like this is needed to avoid > warnings similar to what you did for omap3. Thanks Tony! I've had a brief look at omap2_pm_idle() and do I understand it right that something like the below patch would reduce it to a simple 'WFI'? What do I do with the rest of that code, because I don't think this thing has a cpuidle driver to take over, effectively turning it into dead code. --- a/arch/arm/mach-omap2/pm24xx.c +++ b/arch/arm/mach-omap2/pm24xx.c @@ -126,10 +126,20 @@ static int omap2_allow_mpu_retention(voi return 1; } -static void omap2_enter_mpu_retention(void) +static void omap2_do_wfi(void) { const int zero = 0; + /* WFI */ + asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); +} + +#if 0 +/* + * possible cpuidle implementation between WFI and full_retention above + */ +static void omap2_enter_mpu_retention(void) +{ /* The peripherals seem not to be able to wake up the MPU when * it is in retention mode. */ if (omap2_allow_mpu_retention()) { @@ -146,8 +157,7 @@ static void omap2_enter_mpu_retention(vo pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); } - /* WFI */ - asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); + omap2_do_wfi(); pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); } @@ -161,6 +171,7 @@ static int omap2_can_sleep(void) return 1; } +#endif static void omap2_pm_idle(void) { @@ -169,6 +180,7 @@ static void omap2_pm_idle(void) if (omap_irq_pending()) return; +#if 0 error = cpu_cluster_pm_enter(); if (error || !omap2_can_sleep()) { omap2_enter_mpu_retention(); @@ -179,6 +191,9 @@ static void omap2_pm_idle(void) out_cpu_cluster_pm: cpu_cluster_pm_exit(); +#else + omap2_do_wfi(); +#endif } static void __init prcm_setup_regs(void)
Hi, Adding Aaro Koskinen and Peter Vasil for pm24xx for n800 and n810 related idle. * Peter Zijlstra <peterz@infradead.org> [220614 22:07]: > On Mon, Jun 13, 2022 at 03:39:05PM +0300, Tony Lindgren wrote: > > OMAP4 uses full SoC suspend modes as idle states, as such it needs the > > whole power-domain and clock-domain code from the idle path. > > > > All that code is not suitable to run with RCU disabled, as such push > > RCU-idle deeper still. > > > > Signed-off-by: Tony Lindgren <tony@atomide.com> > > --- > > > > Peter here's one more for your series, looks like this is needed to avoid > > warnings similar to what you did for omap3. > > Thanks Tony! > > I've had a brief look at omap2_pm_idle() and do I understand it right > that something like the below patch would reduce it to a simple 'WFI'? Yes that should do for omap2_do_wfi(). > What do I do with the rest of that code, because I don't think this > thing has a cpuidle driver to take over, effectively turning it into > dead code. As we are establishing a policy where deeper idle states must be handled by cpuidle, and for most part that has been the case for at least 10 years, I'd just drop the unused functions with an explanation in the patch why we're doing it. Or the functions could be tagged with __maybe_unused if folks prefer that. In the pm24xx case we are not really causing a regression for users as there are still pending patches to make n800 and n810 truly usable with the mainline kernel. At least the PMIC and LCD related patches need some work [0]. The deeper idle states can be added back later using cpuidle as needed so we have a clear path. Aaro & Peter V, do you have any better suggestions here as this will mostly affect you guys currently? Regards, Tony [0] https://lore.kernel.org/linux-omap/20211224214512.1583430-1-peter.vasil@gmail.com/ > --- a/arch/arm/mach-omap2/pm24xx.c > +++ b/arch/arm/mach-omap2/pm24xx.c > @@ -126,10 +126,20 @@ static int omap2_allow_mpu_retention(voi > return 1; > } > > -static void omap2_enter_mpu_retention(void) > +static void omap2_do_wfi(void) > { > const int zero = 0; > > + /* WFI */ > + asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); > +} > + > +#if 0 > +/* > + * possible cpuidle implementation between WFI and full_retention above > + */ > +static void omap2_enter_mpu_retention(void) > +{ > /* The peripherals seem not to be able to wake up the MPU when > * it is in retention mode. */ > if (omap2_allow_mpu_retention()) { > @@ -146,8 +157,7 @@ static void omap2_enter_mpu_retention(vo > pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); > } > > - /* WFI */ > - asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); > + omap2_do_wfi(); > > pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); > } > @@ -161,6 +171,7 @@ static int omap2_can_sleep(void) > > return 1; > } > +#endif > > static void omap2_pm_idle(void) > { > @@ -169,6 +180,7 @@ static void omap2_pm_idle(void) > if (omap_irq_pending()) > return; > > +#if 0 > error = cpu_cluster_pm_enter(); > if (error || !omap2_can_sleep()) { > omap2_enter_mpu_retention(); > @@ -179,6 +191,9 @@ static void omap2_pm_idle(void) > > out_cpu_cluster_pm: > cpu_cluster_pm_exit(); > +#else > + omap2_do_wfi(); > +#endif > } > > static void __init prcm_setup_regs(void)
diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h --- a/arch/arm/mach-omap2/common.h +++ b/arch/arm/mach-omap2/common.h @@ -284,11 +284,13 @@ extern u32 omap4_get_cpu1_ns_pa_addr(void); #if defined(CONFIG_SMP) && defined(CONFIG_PM) extern int omap4_mpuss_init(void); -extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state); +extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state, + bool rcuidle); extern int omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state); #else static inline int omap4_enter_lowpower(unsigned int cpu, - unsigned int power_state) + unsigned int power_state, + bool rcuidle) { cpu_do_idle(); return 0; diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c --- a/arch/arm/mach-omap2/cpuidle44xx.c +++ b/arch/arm/mach-omap2/cpuidle44xx.c @@ -105,9 +105,7 @@ static int omap_enter_idle_smp(struct cpuidle_device *dev, } raw_spin_unlock_irqrestore(&mpu_lock, flag); - cpuidle_rcu_enter(); - omap4_enter_lowpower(dev->cpu, cx->cpu_state); - cpuidle_rcu_exit(); + omap4_enter_lowpower(dev->cpu, cx->cpu_state, true); raw_spin_lock_irqsave(&mpu_lock, flag); if (cx->mpu_state_vote == num_online_cpus()) @@ -186,10 +184,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev, } } - cpuidle_rcu_enter(); - omap4_enter_lowpower(dev->cpu, cx->cpu_state); + omap4_enter_lowpower(dev->cpu, cx->cpu_state, true); cpu_done[dev->cpu] = true; - cpuidle_rcu_exit(); /* Wakeup CPU1 only if it is not offlined */ if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) { diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c --- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c +++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c @@ -33,6 +33,7 @@ * and first to wake-up when MPUSS low power states are excercised */ +#include <linux/cpuidle.h> #include <linux/kernel.h> #include <linux/io.h> #include <linux/errno.h> @@ -214,6 +215,7 @@ static void __init save_l2x0_context(void) * of OMAP4 MPUSS subsystem * @cpu : CPU ID * @power_state: Low power state. + * @rcuidle: RCU needs to be idled * * MPUSS states for the context save: * save_state = @@ -222,7 +224,8 @@ static void __init save_l2x0_context(void) * 2 - CPUx L1 and logic lost + GIC lost: MPUSS OSWR * 3 - CPUx L1 and logic lost + GIC + L2 lost: DEVICE OFF */ -int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state) +int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state, + bool rcuidle) { struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu); unsigned int save_state = 0, cpu_logic_state = PWRDM_POWER_RET; @@ -268,6 +271,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state) cpu_clear_prev_logic_pwrst(cpu); pwrdm_set_next_pwrst(pm_info->pwrdm, power_state); pwrdm_set_logic_retst(pm_info->pwrdm, cpu_logic_state); + + if (rcuidle) + cpuidle_rcu_enter(); + set_cpu_wakeup_addr(cpu, __pa_symbol(omap_pm_ops.resume)); omap_pm_ops.scu_prepare(cpu, power_state); l2x0_pwrst_prepare(cpu, save_state); @@ -283,6 +290,9 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state) if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD) && cpu) gic_dist_enable(); + if (rcuidle) + cpuidle_rcu_exit(); + /* * Restore the CPUx power state to ON otherwise CPUx * power domain can transitions to programmed low power diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c --- a/arch/arm/mach-omap2/pm44xx.c +++ b/arch/arm/mach-omap2/pm44xx.c @@ -76,7 +76,7 @@ static int omap4_pm_suspend(void) * domain CSWR is not supported by hardware. * More details can be found in OMAP4430 TRM section 4.3.4.2. */ - omap4_enter_lowpower(cpu_id, cpu_suspend_state); + omap4_enter_lowpower(cpu_id, cpu_suspend_state, false); /* Restore next powerdomain state */ list_for_each_entry(pwrst, &pwrst_list, node) {
OMAP4 uses full SoC suspend modes as idle states, as such it needs the whole power-domain and clock-domain code from the idle path. All that code is not suitable to run with RCU disabled, as such push RCU-idle deeper still. Signed-off-by: Tony Lindgren <tony@atomide.com> --- Peter here's one more for your series, looks like this is needed to avoid warnings similar to what you did for omap3. --- arch/arm/mach-omap2/common.h | 6 ++++-- arch/arm/mach-omap2/cpuidle44xx.c | 8 ++------ arch/arm/mach-omap2/omap-mpuss-lowpower.c | 12 +++++++++++- arch/arm/mach-omap2/pm44xx.c | 2 +- 4 files changed, 18 insertions(+), 10 deletions(-)