[PATCH v2] ARM: EXYNOS: Use MCPM call-backs to support S2R on Exynos5420

Hi Nicolas,

On Tue, Jul 1, 2014 at 9:49 AM, Nicolas Pitre [off-list ref] wrote:

On Mon, 30 Jun 2014, Abhilash Kesavan wrote:

quoted

Use the MCPM layer to handle core suspend/resume on Exynos5420.
Also, restore the entry address setup code post-resume.

Signed-off-by: Abhilash Kesavan <redacted>
---

[...]

Could you tell me more about this?

quoted

@@ -150,7 +153,13 @@ static void exynos_power_down(void)
      BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
      cpu_use_count[cpu][cluster]--;
      if (cpu_use_count[cpu][cluster] == 0) {
-             exynos_cpu_power_down(cpunr);
+             /*
+              * Bypass power down for CPU0 during suspend. This is being
+              * taken care by the SYS_PWR_CFG bit in CORE0_SYS_PWR_REG.
+              */
+             if ((cpunr != 0) ||
+             (__raw_readl(pmu_base_addr + S5P_INFORM1) != S5P_CHECK_SLEEP))
+                     exynos_cpu_power_down(cpunr);

What happens if CPU0 is the first in the cluster to be idled?  Will it
remain powered up until all the others have gone idle too?

This check is only for handling the S2R CPU0 case. In case of
idle/switching the S5P_CHECK_SLEEP flag would not be set and hence
there would be no change in behavior for them.
During suspend, we enable the ARM_USE_STANDBY_WFI0 bit which tells the
PMU when the CPU0 is ready to be suspended. This in conjunction with
the sleep state core configuration (setting SYS_PWR_REG low) causes
the CPU0 to go down. We should not write to the CPU0 power
configuration register (exynos_cpu_power_down) along with this during
suspend.

Regards,
Abhilash

Nicolas