ARM: EXYNOS: Fix failed second suspend on Exynos4

On Exynos4412 boards (Trats2, Odroid U3) after enabling L2 cache in
56b60b8bce4a ("ARM: 8265/1: dts: exynos4: Add nodes for L2 cache
controller") the second suspend to RAM failed. First suspend worked fine
but the next one hang just after powering down of secondary CPUs (system
consumed energy as it would be running but was not responsive).

The issue was caused by enabling delayed reset assertion for CPU0 just
after issuing power down of cores. This was introduced for Exynos4 in
13cfa6c4f7fa ("ARM: EXYNOS: Fix CPU idle clock down after CPU off").

The whole behavior is not well documented but after checking with vendor
code this should be done like this (on Exynos4):
1. Enable delayed reset assertion when system is running (for all CPUs).
2. Disable delayed reset assertion before suspending the system.
   This can be done after powering off secondary CPUs.
3. Re-enable the delayed reset assertion when system is resumed.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: 13cfa6c4f7fa ("ARM: EXYNOS: Fix CPU idle clock down after CPU off")
Cc: <stable@vger.kernel.org>
Tested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>

diff --git a/arch/arm/mach-exynos/exynos.c b/arch/arm/mach-exynos/exynos.c
index 5917a30eee33f286c80708dfb84cdd610bd2dd9d..c3bfbba3006d8fbd51c328b8c964434bf6fa1ea3 100644 (file)
--- a/arch/arm/mach-exynos/exynos.c
+++ b/arch/arm/mach-exynos/exynos.c
@@ -179,7 +179,7 @@ static void __init exynos_init_io(void)
  */
 void exynos_set_delayed_reset_assertion(bool enable)
 {
-       if (of_machine_is_compatible("samsung,exynos4")) {
+       if (soc_is_exynos4()) {
                unsigned int tmp, core_id;
 
                for (core_id = 0; core_id < num_possible_cpus(); core_id++) {