On OMAP4430 HS / EMU chips, ROM code appears to re-configure L4PER domain
next powerstate during wakeup from OSWR / OFF, programming it to ON.
This will prevent successive entries to cpuidle retention / off, until
kernel decices to change the L4PER target state, which can be delayed
for a very long time as kernel is lazy programming the target state.
This patch fixes the issue within the low power OSWR / OFF mode code, so
that this register is saved / restored across MPU OSWR / OFF state.
This problem seems to only occur with OMAP4430 HS/EMU, it does not impact
OMAP4460+ or GP devices.
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
arch/arm/mach-omap2/omap-mpuss-lowpower.c | 39 ++++++++++++++++++++++++++++-
arch/arm/mach-omap2/pm.h | 1 +
arch/arm/mach-omap2/pm44xx.c | 10 +++++++
3 files changed, 49 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
index 0e5f81b..963a61b 100644
--- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
+++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
@@ -52,6 +52,7 @@
#include <plat/omap44xx.h>
+#include "iomap.h"
#include "common.h"
#include "omap4-sar-layout.h"
#include "pm.h"
@@ -97,6 +98,15 @@ static inline void set_cpu_next_pwrst(unsigned int cpu_id,
omap_set_pwrdm_state(pm_info->pwrdm, power_state);
}
+struct reg_tuple {
+ void __iomem *addr;
+ u32 val;
+};
+
+static struct reg_tuple l4per_reg[] = {
+ {.addr = OMAP4430_PM_L4PER_PWRSTCTRL},
+};
+
/*
* Read CPU's previous power state
*/
@@ -215,6 +225,28 @@ static void save_l2x0_context(void)
{}
#endif
+static inline void save_l4per_regs(void)
+{
+ int i;
+
+ if (!IS_PM44XX_ERRATUM(PM_OMAP4_ROM_L4PER_ERRATUM_PWSTCT))
+ return;
+
+ for (i = 0; i < ARRAY_SIZE(l4per_reg); i++)
+ l4per_reg[i].val = __raw_readl(l4per_reg[i].addr);
+}
+
+static inline void restore_l4per_regs(void)
+{
+ int i;
+
+ if (!IS_PM44XX_ERRATUM(PM_OMAP4_ROM_L4PER_ERRATUM_PWSTCT))
+ return;
+
+ for (i = 0; i < ARRAY_SIZE(l4per_reg); i++)
+ __raw_writel(l4per_reg[i].val, l4per_reg[i].addr);
+}
+
/**
* omap4_enter_lowpower: OMAP4 MPUSS Low Power Entry Function
* The purpose of this function is to manage low power programming
@@ -265,8 +297,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
* In MPUSS OSWR or device OFF, interrupt controller context is lost.
*/
mpuss_clear_prev_logic_pwrst();
- if (pwrdm_read_next_func_pwrst(mpuss_pd) == PWRDM_FUNC_PWRST_OSWR)
+ if (pwrdm_read_next_func_pwrst(mpuss_pd) == PWRDM_FUNC_PWRST_OSWR) {
+ save_l4per_regs();
save_state = 2;
+ }
cpu_clear_prev_logic_pwrst(cpu);
set_cpu_next_pwrst(cpu, power_state);
@@ -289,6 +323,9 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
wakeup_cpu = smp_processor_id();
set_cpu_next_pwrst(wakeup_cpu, PWRDM_FUNC_PWRST_ON);
+ if (omap4_mpuss_read_prev_context_state())
+ restore_l4per_regs();
+
pwrdm_post_transition();
return 0;
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index d95d1d0..adce520 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -89,6 +89,7 @@ static inline void enable_omap3630_toggle_l2_on_restore(void) { }
#endif /* defined(CONFIG_PM) && defined(CONFIG_ARCH_OMAP3) */
#define PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD (1 << 0)
+#define PM_OMAP4_ROM_L4PER_ERRATUM_PWSTCT (1 << 1)
#if defined(CONFIG_ARCH_OMAP4)
extern u16 pm44xx_errata;
diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
index eb3e073..1e98909 100644
--- a/arch/arm/mach-omap2/pm44xx.c
+++ b/arch/arm/mach-omap2/pm44xx.c
@@ -194,6 +194,16 @@ int __init omap4_pm_init(void)
(void) clkdm_for_each(omap_pm_clkdms_setup, NULL);
+ /*
+ * ROM core appears to modify the L4PER powerstate control register
+ * during wakeup from OSWR / OFF, which will prevent further low
+ * power state transitions until the register is re-programmed.
+ * Thus, we must save / restore the register during idle. This
+ * seems to happen only on omap4430, on HS / EMU chips only.
+ */
+ if (cpu_is_omap443x() && omap_type() != OMAP2_DEVICE_TYPE_GP)
+ pm44xx_errata |= PM_OMAP4_ROM_L4PER_ERRATUM_PWSTCT;
+
#ifdef CONFIG_SUSPEND
omap_pm_suspend = omap4_pm_suspend;
#endif
--
1.7.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
