In order to bring up secondary CPUs main CPU write trampoline
code to SRAM. The trampoline code is written while secondary
CPUs are powered on (at least that true for RK3188 CPU).
Sometimes that leads to kernel hang. Probably because secondary
CPU execute trampoline code while kernel doesn't expect.

The patch moves SRAM initialization step to the point where all
secondary CPUs are powered down.

That fixes rarely hangs on RK3188:
[    0.091568] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.091996] rockchip_smp_prepare_cpus: ncores 4

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
---
 arch/arm/mach-rockchip/platsmp.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
index 36915a073c23..f432d22bfed8 100644
--- a/arch/arm/mach-rockchip/platsmp.c
+++ b/arch/arm/mach-rockchip/platsmp.c
@@ -279,11 +279,6 @@ static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
 	}
 
 	if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9) {
-		if (rockchip_smp_prepare_sram(node)) {
-			of_node_put(node);
-			return;
-		}
-
 		/* enable the SCU power domain */
 		pmu_set_power_domain(PMU_PWRDN_SCU, true);
 
@@ -316,11 +311,19 @@ static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
 		asm ("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
 		ncores = ((l2ctlr >> 24) & 0x3) + 1;
 	}
-	of_node_put(node);
 
 	/* Make sure that all cores except the first are really off */
 	for (i = 1; i < ncores; i++)
 		pmu_set_power_domain(0 + i, false);
+
+	if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9) {
+		if (rockchip_smp_prepare_sram(node)) {
+			of_node_put(node);
+			return;
+		}
+	}
+
+	of_node_put(node);
 }
 
 static void __init rk3036_smp_prepare_cpus(unsigned int max_cpus)
-- 
2.43.0

On Thu, 03 Jul 2025 17:04:53 +0300, Alexander Kochetkov wrote:
> In order to bring up secondary CPUs main CPU write trampoline
> code to SRAM. The trampoline code is written while secondary
> CPUs are powered on (at least that true for RK3188 CPU).
> Sometimes that leads to kernel hang. Probably because secondary
> CPU execute trampoline code while kernel doesn't expect.
> 
> The patch moves SRAM initialization step to the point where all
> secondary CPUs are powered down.
> 
> [...]

Applied, thanks!

Gave this a spin on rk3066 + rk3188 + (not-A9) rk3288.
Both the affected SoCs as well as the rk3288 booted fine.


[1/1] ARM: rockchip: fix kernel hang during smp initialization
      commit: 7cdb433bb44cdc87dc5260cdf15bf03cc1cd1814

Best regards,
-- 
Heiko Stuebner <heiko@sntech.de>