[PATCH 1/3] MIPS: Stop secondary CPUs before platform restart/halt/poweroff

[PATCH 1/3] MIPS: Stop secondary CPUs before platform restart/halt/poweroff

[Rany Hany]

smp_send_stop() was placed after the platform restart, halt, and
power-off callbacks. These callbacks never return, so smp_send_stop()
was dead code and secondary CPUs were never stopped before the system
reset. Move smp_send_stop() before the callbacks.

Signed-off-by: Rany Hany <rany_hany@riseup.net>
---
 arch/mips/kernel/reset.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kernel/reset.c b/arch/mips/kernel/reset.c
index e7ce07b3e..12c54d1b7 100644
--- a/arch/mips/kernel/reset.c
+++ b/arch/mips/kernel/reset.c
@@ -87,13 +87,14 @@ static void machine_hang(void)
 
 void machine_restart(char *command)
 {
-	if (_machine_restart)
-		_machine_restart(command);
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	if (_machine_restart)
+		_machine_restart(command);
+
 	do_kernel_restart(command);
 	mdelay(1000);
 	pr_emerg("Reboot failed -- System halted\n");
@@ -102,23 +103,25 @@ void machine_restart(char *command)
 
 void machine_halt(void)
 {
-	if (_machine_halt)
-		_machine_halt();
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	if (_machine_halt)
+		_machine_halt();
+
 	machine_hang();
 }
 
 void machine_power_off(void)
 {
-	do_kernel_power_off();
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	do_kernel_power_off();
+
 	machine_hang();
 }
-- 
2.53.0

[PATCH 0/3] Fix MT7621 restart deadlock

[Rany Hany]

These patches fix an issue on some MT7621 devices where the reboot
hangs. They were submitted to OpenWrt and have been merged.

The first two patches aren't particularly remarkable as they just
align MIPS with ARM behavior and are required for the full fix.

The last patch is the most interesting as it uses CPC to transition
the CPU to clock off state. It is not clear to me why this is required
but without it it ends up hanging. Initially only flushing d-cache
and using TCHalt was attempted but ClkOff appears to be necessary. 

This fix was only tested on ASUS RT-AX53U as I don't have other
MT7621 devices with this problem.

Unrelated note:

Sorry I had to resend this as my Thunderbird client was not properly
setup for this. I used imap-send which just caused issues. I am not
sure how I previously setup Thunderbird so that it groups the patches
in one thread.

In any case, I ended up just using send-email as I didn't want to mess
with Thunderbird again.

Rany Hany (3):
  MIPS: Stop secondary CPUs before platform restart/halt/poweroff
  MIPS: SMP: Wait for secondary CPUs to stop in smp_send_stop()
  MIPS: SMP: Properly stop secondary CPUs for restart

 arch/mips/kernel/reset.c | 19 ++++++-----
 arch/mips/kernel/smp.c   | 68 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 78 insertions(+), 9 deletions(-)

-- 
2.53.0

[PATCH 1/3] MIPS: Stop secondary CPUs before platform restart/halt/poweroff

[Rany Hany]

smp_send_stop() was placed after the platform restart, halt, and
power-off callbacks. These callbacks never return, so smp_send_stop()
was dead code and secondary CPUs were never stopped before the system
reset.

Move smp_send_stop() before the callbacks.

Signed-off-by: Rany Hany <rany_hany@riseup.net>
---
 arch/mips/kernel/reset.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kernel/reset.c b/arch/mips/kernel/reset.c
index e7ce07b3e..12c54d1b7 100644
--- a/arch/mips/kernel/reset.c
+++ b/arch/mips/kernel/reset.c
@@ -87,13 +87,14 @@ static void machine_hang(void)
 
 void machine_restart(char *command)
 {
-	if (_machine_restart)
-		_machine_restart(command);
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	if (_machine_restart)
+		_machine_restart(command);
+
 	do_kernel_restart(command);
 	mdelay(1000);
 	pr_emerg("Reboot failed -- System halted\n");
@@ -102,23 +103,25 @@ void machine_restart(char *command)
 
 void machine_halt(void)
 {
-	if (_machine_halt)
-		_machine_halt();
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	if (_machine_halt)
+		_machine_halt();
+
 	machine_hang();
 }
 
 void machine_power_off(void)
 {
-	do_kernel_power_off();
-
 #ifdef CONFIG_SMP
 	preempt_disable();
 	smp_send_stop();
 #endif
+
+	do_kernel_power_off();
+
 	machine_hang();
 }
-- 
2.53.0