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ARM: OMAP4+: SMP: use lockless clkdm/pwrdm api in omap4_boot_secondary
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OMAP CPU hotplug uses cpu1's clocks and power domains for CPU1 wake up
from low power states (or turn on CPU1). This part of code is also
part of system suspend (disable_nonboot_cpus()).
>From other side, cpu1's clocks and power domains are used by CPUIdle. All above
functionality is mutually exclusive and, therefore, lockless clkdm/pwrdm api
can be used in omap4_boot_secondary().

This fixes below back-trace on -RT which is triggered by
pwrdm_lock/unlock():

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
 in_atomic(): 1, irqs_disabled(): 0, pid: 118, name: sh
 9 locks held by sh/118:
  #0:  (sb_writers#4){.+.+.+}, at: [<c0144a6c>] vfs_write+0x13c/0x164
  coreos#1:  (&of->mutex){+.+.+.}, at: [<c01b4c70>] kernfs_fop_write+0x48/0x19c
  coreos#2:  (s_active#24){.+.+.+}, at: [<c01b4c78>] kernfs_fop_write+0x50/0x19c
  coreos#3:  (device_hotplug_lock){+.+.+.}, at: [<c03cbff0>] lock_device_hotplug_sysfs+0xc/0x4c
  coreos#4:  (&dev->mutex){......}, at: [<c03cd284>] device_online+0x14/0x88
  coreos#5:  (cpu_add_remove_lock){+.+.+.}, at: [<c003af90>] cpu_up+0x50/0x1a0
  coreos#6:  (cpu_hotplug.lock){++++++}, at: [<c003ae48>] cpu_hotplug_begin+0x0/0xc4
  coreos#7:  (cpu_hotplug.lock#2){+.+.+.}, at: [<c003aec0>] cpu_hotplug_begin+0x78/0xc4
  coreos#8:  (boot_lock){+.+...}, at: [<c002b254>] omap4_boot_secondary+0x1c/0x178
 Preemption disabled at:[<  (null)>]   (null)

 CPU: 0 PID: 118 Comm: sh Not tainted 4.1.12-rt11-01998-gb4a62c3-dirty coreos#137
 Hardware name: Generic DRA74X (Flattened Device Tree)
 [<c0017574>] (unwind_backtrace) from [<c0013be8>] (show_stack+0x10/0x14)
 [<c0013be8>] (show_stack) from [<c05a8670>] (dump_stack+0x80/0x94)
 [<c05a8670>] (dump_stack) from [<c05ad158>] (rt_spin_lock+0x24/0x54)
 [<c05ad158>] (rt_spin_lock) from [<c0030dac>] (clkdm_wakeup+0x10/0x2c)
 [<c0030dac>] (clkdm_wakeup) from [<c002b2c0>] (omap4_boot_secondary+0x88/0x178)
 [<c002b2c0>] (omap4_boot_secondary) from [<c0015d00>] (__cpu_up+0xc4/0x164)
 [<c0015d00>] (__cpu_up) from [<c003b09c>] (cpu_up+0x15c/0x1a0)
 [<c003b09c>] (cpu_up) from [<c03cd2d4>] (device_online+0x64/0x88)
 [<c03cd2d4>] (device_online) from [<c03cd360>] (online_store+0x68/0x74)
 [<c03cd360>] (online_store) from [<c01b4ce0>] (kernfs_fop_write+0xb8/0x19c)
 [<c01b4ce0>] (kernfs_fop_write) from [<c0144124>] (__vfs_write+0x20/0xd8)
 [<c0144124>] (__vfs_write) from [<c01449c0>] (vfs_write+0x90/0x164)
 [<c01449c0>] (vfs_write) from [<c01451e4>] (SyS_write+0x44/0x9c)
 [<c01451e4>] (SyS_write) from [<c0010240>] (ret_fast_syscall+0x0/0x54)
 CPU1: smp_ops.cpu_die() returned, trying to resuscitate

Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
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grygoriyS authored and tmlind committed Nov 25, 2015
1 parent 970259b commit 918af9f
Showing 1 changed file with 3 additions and 3 deletions.
6 changes: 3 additions & 3 deletions arch/arm/mach-omap2/omap-smp.c
Original file line number Diff line number Diff line change
Expand Up @@ -143,9 +143,9 @@ static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
* Ensure that CPU power state is set to ON to avoid CPU
* powerdomain transition on wfi
*/
clkdm_wakeup(cpu1_clkdm);
omap_set_pwrdm_state(cpu1_pwrdm, PWRDM_POWER_ON);
clkdm_allow_idle(cpu1_clkdm);
clkdm_wakeup_nolock(cpu1_clkdm);
pwrdm_set_next_pwrst(cpu1_pwrdm, PWRDM_POWER_ON);
clkdm_allow_idle_nolock(cpu1_clkdm);

if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD)) {
while (gic_dist_disabled()) {
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