[PATCH 14/17] ARM: mvebu: synchronize secondary CPU clocks on resume

Hi Thomas,
On 24/10/2014 13:59, Thomas Petazzoni wrote:

The Armada XP has multiple cores clocked by independent clocks. The
SMP startup code contains a function called set_secondary_cpus_clock()
called in armada_xp_smp_prepare_cpus() to ensure the clocks of the
secondary CPUs match the clock of the boot CPU.

With the introduction of suspend/resume, this operation is no longer
needed when booting the system, but also when existing the suspend to
RAM state. Therefore this commit reworks a bit the logic: instead of
configuring the clock of all secondary CPUs in
armada_xp_smp_prepare_cpus(), we do it on a per-secondary CPU basis in
armada_xp_boot_secondary(), as this function gets called when existing
suspend to RAM for each secondary CPU.

Since the function now only takes care of one CPU, we rename it from
set_secondary_cpus_clock() to set_secondary_cpu_clock(), and it looses
its __init marker, as it is now used beyond the system initialization.

Note that we can't use smp_processor_id() directly, because when
exiting from suspend to RAM, the code is apparently executed with
preemption enabled, so smp_processor_id() is not happy (prints a
warning). We therefore switch to using get_cpu()/put_cpu(), even
though we pretty much have the guarantee that the code starting the
secondary CPUs is going to run on the boot CPU and will not be
migrated.

Acked-by: Gregory CLEMENT <redacted>


Thanks,

Gregory

Signed-off-by: Thomas Petazzoni <redacted>
---
 arch/arm/mach-mvebu/platsmp.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com