From: Kalle Jokiniemi <ext-kalle.jokiniemi@xxxxxxxxx>
The biggest source of latency in idle loop (omap_sram_idle
function) comes from updating the state counters for each
power domain. The two purposes of these counters are to
provide debug data in debugfs, and to keep track of context
losses occurring during idle transitions (off mode counters).
I created new debugfs interface "enable_count" for
enabling the "count" interface, which exposes the debug
part of these counters. The counters are not updated
anymore for CORE ON idle transitions, when the count
interface is disabled. For deeper CORE states, counters
are still updated to preserve context loss tracking.
This change decreases C1/C2 state latency over 100us at
OPP2.
Signed-off-by: Kalle Jokiniemi <ext-kalle.jokiniemi@xxxxxxxxx>
---
arch/arm/mach-omap2/pm-debug.c | 51 ++++++++++++++++++++++++++++++++++++++-
arch/arm/mach-omap2/pm.h | 2 +
arch/arm/mach-omap2/pm34xx.c | 12 +++++----
3 files changed, 58 insertions(+), 7 deletions(-)
diff --git a/arch/arm/mach-omap2/pm-debug.c b/arch/arm/mach-omap2/pm-debug.c
index 5aac64f..76c2696 100644
--- a/arch/arm/mach-omap2/pm-debug.c
+++ b/arch/arm/mach-omap2/pm-debug.c
@@ -37,6 +37,9 @@
#include "prm-regbits-34xx.h"
int omap2_pm_debug;
+static int pm_dbg_count_active;
+static struct dentry *de_pm_debug_count;
+static struct dentry *de_pm_debug;
#define DUMP_PRM_MOD_REG(mod, reg) \
regs[reg_count].name = #mod "." #reg; \
@@ -327,6 +330,11 @@ int pm_dbg_regset_save(int reg_set)
return 0;
}
+int pm_dbg_count_is_active(void)
+{
+ return pm_dbg_count_active;
+}
+
static const char pwrdm_state_names[][4] = {
"OFF",
"RET",
@@ -460,6 +468,40 @@ static const struct file_operations debug_reg_fops = {
.release = single_release,
};
+static int pm_dbg_count_enable_get(void *data, u64 *val)
+{
+ *val = pm_dbg_count_active;
+ return 0;
+}
+
+static int pm_dbg_count_enable_set(void *data, u64 val)
+{
+ if (val > 1) {
+ printk(KERN_ERR "Invalid value! 1 to enable, 0 to disable\n");
+ return -EINVAL;
+ }
+
+ if (val == 1 && !pm_dbg_count_active) {
+ de_pm_debug_count = debugfs_create_file("count", S_IRUGO,
+ de_pm_debug, (void *)DEBUG_FILE_COUNTERS, &debug_fops);
+
+ if (de_pm_debug_count == NULL) {
+ printk(KERN_ERR "Error: could not create debugfs "
+ "entry\n");
+ return -ENOMEM;
+ }
+ pm_dbg_count_active = 1;
+ } else if (val == 0 && pm_dbg_count_active) {
+ debugfs_remove(de_pm_debug_count);
+ de_pm_debug_count = NULL;
+ pm_dbg_count_active = 0;
+ }
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(enable_count_fops, pm_dbg_count_enable_get,
+ pm_dbg_count_enable_set, "%llu\n");
+
int pm_dbg_regset_init(int reg_set)
{
char name[2];
@@ -576,12 +618,17 @@ static int __init pm_dbg_init(void)
return -ENODEV;
}
+ pm_dbg_count_active = 0;
+
d = debugfs_create_dir("pm_debug", NULL);
if (IS_ERR(d))
return PTR_ERR(d);
+ de_pm_debug = d;
+
+ (void) debugfs_create_file("enable_count", S_IRUGO |
+ S_IWUGO, d, &pm_dbg_count_active,
+ &enable_count_fops);
- (void) debugfs_create_file("count", S_IRUGO,
- d, (void *)DEBUG_FILE_COUNTERS, &debug_fops);
(void) debugfs_create_file("time", S_IRUGO,
d, (void *)DEBUG_FILE_TIMERS, &debug_fops);
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index f8d11a2..3f0202b 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -63,12 +63,14 @@ extern int omap2_pm_debug;
extern void pm_dbg_update_time(struct powerdomain *pwrdm, int prev);
extern int pm_dbg_regset_save(int reg_set);
extern int pm_dbg_regset_init(int reg_set);
+extern int pm_dbg_count_is_active(void);
#else
#define omap2_pm_dump(mode, resume, us) do {} while (0);
#define omap2_pm_debug 0
#define pm_dbg_update_time(pwrdm, prev) do {} while (0);
#define pm_dbg_regset_save(reg_set) do {} while (0);
#define pm_dbg_regset_init(reg_set) do {} while (0);
+#define pm_dbg_count_is_active() 0
#endif /* CONFIG_PM_DEBUG */
extern void omap24xx_idle_loop_suspend(void);
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 01260ec..237c819 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -378,15 +378,17 @@ void omap_sram_idle(void)
return;
}
- pwrdm_pre_transition();
+ per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
+ core_next_state = pwrdm_read_next_pwrst(core_pwrdm);
+
+ if (pm_dbg_count_is_active() || (core_next_state != PWRDM_POWER_ON))
+ pwrdm_pre_transition();
/* NEON control */
if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
/* PER */
- per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
- core_next_state = pwrdm_read_next_pwrst(core_pwrdm);
if (per_next_state < PWRDM_POWER_ON) {
omap_uart_prepare_idle(2);
omap2_gpio_prepare_for_idle(per_next_state);
@@ -505,8 +507,8 @@ void omap_sram_idle(void)
omap3_disable_io_chain();
}
-
- pwrdm_post_transition();
+ if (pm_dbg_count_is_active() || (core_next_state != PWRDM_POWER_ON))
+ pwrdm_post_transition();
omap2_clkdm_allow_idle(mpu_pwrdm->pwrdm_clkdms[0]);
}
--
1.5.4.3
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