Re: [PATCH -next] power/domain_governor: fix a compilation error

[Rafael J. Wysocki]

On Thu, Apr 11, 2019 at 3:23 PM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Thu, 11 Apr 2019 at 14:48, Qian Cai <cai@xxxxxx> wrote:
> >
> > The commit 50899f7d5078 ("PM / Domains: Add genpd governor for CPUs")
> > introduced a compilation error on arm64 with CONFIG_CPU_IDLE=n because
> > cpuidle_devices is undefined there.
> >
> > drivers/base/power/domain_governor.o: In function `cpu_power_down_ok':
> > drivers/base/power/domain_governor.c:263: undefined reference to
> > 'cpuidle_devices' ld: drivers/base/power/domain_governor.o: relocation
> > R_AARCH64_ADR_PREL_PG_HI21 against symbol 'cpuidle_devices' which may
> > bind externally can not be used when making a shared object; recompile
> > with -fPIC
> > drivers/base/power/domain_governor.c:263:(.text+0x638): dangerous
> > relocation: unsupported relocation
> > drivers/base/power/domain_governor.c:263: undefined reference to
> > 'cpuidle_devices'
> > make: *** [Makefile:1047: vmlinux] Error 1
> >
> > Signed-off-by: Qian Cai <cai@xxxxxx>
>
> Qian, thanks for you patch!
>
> > ---
> >  drivers/base/power/domain_governor.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
> > index 39c8a699cb53..252d88fcf760 100644
> > --- a/drivers/base/power/domain_governor.c
> > +++ b/drivers/base/power/domain_governor.c
> > @@ -270,11 +270,13 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd)
> >          */
> >         domain_wakeup = ktime_set(KTIME_SEC_MAX, 0);
> >         for_each_cpu_and(cpu, genpd->cpus, cpu_online_mask) {
> > -               dev = per_cpu(cpuidle_devices, cpu);
> > -               if (dev) {
> > -                       next_hrtimer = READ_ONCE(dev->next_hrtimer);
> > -                       if (ktime_before(next_hrtimer, domain_wakeup))
> > -                               domain_wakeup = next_hrtimer;
> > +               if (IS_ENABLED(CONFIG_CPU_IDLE)) {
> > +                       dev = per_cpu(cpuidle_devices, cpu);
> > +                       if (dev) {
> > +                               next_hrtimer = READ_ONCE(dev->next_hrtimer);
> > +                               if (ktime_before(next_hrtimer, domain_wakeup))
> > +                                       domain_wakeup = next_hrtimer;
> > +                       }
>
> This works as quick fix, but I think there is two possible options
> that is probably better in long run.
>
> 1) Extend the cpuidle interface with a new function:
>
> struct cpuidle_device *cpuidle_get_cpu_device(unsigned int cpu)
>
> Then when CONFIG_CPU_IDLE is unset, we can just have a stub function
> returning NULL.

So why exactly cpu_power_down_ok() would be still needed with
CONFIG_CPU_IDLE unset?

> 2) Have the struct dev_power_governor pm_domain_cpu_gov to be defined
> (and the corresponding functionality), but only when CONFIG_CPU_IDLE
> is set and when CONFIG_PM_GENERIC_DOMAINS is set.

So please do that.

Can you please send a replacement patch for the [4/4] in the series
with this fixed?