[PATCH v5 1/3] ARM: rockchip: fix the CPU soft reset

[Caesar Wang]

We need different orderings when turning a core on and turning a core
off.  In one case we need to assert reset before turning power off.
In ther other case we need to turn power on and the deassert reset.

In general, the correct flow is:

CPU off:
    reset_control_assert
    regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), BIT(pd))
    wait_for_power_domain_to_turn_off
CPU on:
    regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), 0)
    wait_for_power_domain_to_turn_on
    reset_control_deassert

This is needed for stressing CPU up/down, as per:
    cd /sys/devices/system/cpu/
    for i in $(seq 10000); do
        echo "================= $i ============"
        for j in $(seq 100); do
            while [[ "$(cat cpu1/online)$(cat cpu2/online)$(cat cpu3/online)" != "000"" ]]
                echo 0 > cpu1/online
                echo 0 > cpu2/online
                echo 0 > cpu3/online
            done
            while [[ "$(cat cpu1/online)$(cat cpu2/online)$(cat cpu3/online)" != "111" ]]; do
                echo 1 > cpu1/online
                echo 1 > cpu2/online
                echo 1 > cpu3/online
            done
        done
    done

The following is reproducile log:
    [34466.186812] PM: noirq suspend of devices complete after 0.669 msecs
    [34466.186824] Disabling non-boot CPUs ...
    [34466.187509] CPU1: shutdown
    [34466.188672] CPU2: shutdown
    [34473.736627] Kernel panic - not syncing:Watchdog detected hard LOCKUP on cpu 0
    .......
or others similar log:
    .......
    [ 4072.454453] CPU1: shutdown
    [ 4072.504436] CPU2: shutdown
    [ 4072.554426] CPU3: shutdown
    [ 4072.577827] CPU1: Booted secondary processor
    [ 4072.582611] CPU2: Booted secondary processor
    [ 4072.587426] CPU3: Booted secondary processor
    <hang>

Signed-off-by: Caesar Wang <wxt at rock-chips.com>
Reviewed-by: Doug Anderson <dianders at chromium.org>

Changes in v5:
    - back to v2 cpu on/off flow, As Heiko point out in patch v3.
    - delay more time in rockchip_boot_secondary().
    From CPU up/down tests, Needed more time to complete CPU process.
    In order to ensure a more, Here that be delayed 1ms.

Changes in v4:
    - Add reset_control_put(rstc) for the non-error case.

Changes in v3:
    - FIx the PATCH v2, it doesn't work on chromium 3.14.

Changes in v2:
    - As Heiko suggestion, re-adjust the cpu on/off flow.
    CPU off:
    reset_control_assert
    regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), BIT(pd))
    wait_for_power_domain_to_turn_off
    CPU on:
    regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), 0)
    wait_for_power_domain_to_turn_on
    reset_control_deassert

---

 arch/arm/mach-rockchip/platsmp.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
index 5b4ca3c..bd40852 100644
--- a/arch/arm/mach-rockchip/platsmp.c
+++ b/arch/arm/mach-rockchip/platsmp.c
@@ -72,6 +72,7 @@ static struct reset_control *rockchip_get_core_reset(int cpu)
 static int pmu_set_power_domain(int pd, bool on)
 {
 	u32 val = (on) ? 0 : BIT(pd);
+	struct reset_control *rstc = rockchip_get_core_reset(pd);
 	int ret;
 
 	/*
@@ -80,20 +81,15 @@ static int pmu_set_power_domain(int pd, bool on)
 	 * processor is powered down.
 	 */
 	if (read_cpuid_part() != ARM_CPU_PART_CORTEX_A9) {
-		struct reset_control *rstc = rockchip_get_core_reset(pd);
-
+		/* We only require the reset on the RK3288 at the moment */
 		if (IS_ERR(rstc)) {
 			pr_err("%s: could not get reset control for core %d\n",
 			       __func__, pd);
 			return PTR_ERR(rstc);
 		}
 
-		if (on)
-			reset_control_deassert(rstc);
-		else
+		if (!on)
 			reset_control_assert(rstc);
-
-		reset_control_put(rstc);
 	}
 
 	ret = regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), val);
@@ -112,6 +108,12 @@ static int pmu_set_power_domain(int pd, bool on)
 		}
 	}
 
+	if (read_cpuid_part() != ARM_CPU_PART_CORTEX_A9 && on)
+		reset_control_deassert(rstc);
+
+	if (!IS_ERR(rstc))
+		reset_control_put(rstc);
+
 	return 0;
 }
 
@@ -148,7 +150,7 @@ static int __cpuinit rockchip_boot_secondary(unsigned int cpu,
 		 * sram_base_addr + 4: 0xdeadbeaf
 		 * sram_base_addr + 8: start address for pc
 		 * */
-		udelay(10);
+		mdelay(1);
 		writel(virt_to_phys(rockchip_secondary_startup),
 			sram_base_addr + 8);
 		writel(0xDEADBEAF, sram_base_addr + 4);
-- 
1.9.1