Hi,
> > I think we have now all the pieces here to get stable cpuidle +
> > pm_idle + suspend + off mode with minimal configuration on SDP
> > board. Could you Rajendra now gather these together and prepare new
> > patch set in sensible format?
>
> Yes, I will do that. Will re-send the complete patch set with all the
> fixes in place.
I'll add a couple notes based on recent changes in internal code.
Code has moved to using the safe_idle method like reference Intel driver code uses.
- This removes for loop backing up to 1st non-BM state and makes idle path faster.
- The biggest power-performance gain comes by making sure a INACTIVE state is hit. If there is BM activity chances are MPU will be needed anyway and going to OFF probably isn't a win. Getting 98% savings is ok.
Slowness on serial is there anytime you hit INACTIVE if you don't have the UART-NO-IDLE-ON-TX workaround in tree. This is not in Tony's tree yet and probably should be if the UART is bothering you. Choosing a non-WFI state penalty like your patch did is too expensive from a power standpoint for the effect.
Below patches for comment.
Regards,
Richard W.
--- arch/arm/mach-omap2/pm_idle_34xx.c@@/LINUX-GIT-2.6K_INT_FLOAT_4.0 2008-07-02 11:39:50.000000000 -0500
+++ arch/arm/mach-omap2/pm_idle_34xx.c 2008-07-04 11:54:15.000000000 -0500
@@ -706,32 +706,15 @@ return_sleep_time:
static int omap3_enter_idle_bm(struct cpuidle_device *dev,
struct cpuidle_state *state)
{
- struct cpuidle_state *new_state = NULL;
- int i, j;
-
if ((state->flags & CPUIDLE_FLAG_CHECK_BM) && omap3_idle_bm_check()) {
-
- /* Find current state in list */
- for (i = 0; i < OMAP3_MAX_STATES; i++)
- if (state == &dev->states[i])
- break;
- BUG_ON(i == OMAP3_MAX_STATES);
-
- /* Back up to non 'CHECK_BM' state */
- for (j = i - 1; j > 0; j--) {
- struct cpuidle_state *s = &dev->states[j];
-
- if (!(s->flags & CPUIDLE_FLAG_CHECK_BM)) {
- new_state = s;
- break;
- }
+ if (dev->safe_state)
+ return dev->safe_state->enter(dev, dev->safe_state);
+ else {
+ omap_sram_idle();
+ return 0;
}
-
- pr_debug("%s: Bus activity: Entering %s (instead of %s)\n",
- __FUNCTION__, new_state->name, state->name);
}
-
- return omap3_enter_idle(dev, new_state ? : state);
+ return omap3_enter_idle(dev, state);
}
DEFINE_PER_CPU(struct cpuidle_device, omap3_idle_dev);
@@ -766,8 +749,8 @@ void omap_init_power_states(void)
omap3_power_states[OMAP3_STATE_C2].core_state = PRCM_CORE_ACTIVE;
omap3_power_states[OMAP3_STATE_C2].flags = CPUIDLE_FLAG_TIME_VALID |
CPUIDLE_FLAG_BALANCED;
- omap3_power_states[OMAP3_STATE_C3].valid = 1;
+ omap3_power_states[OMAP3_STATE_C3].valid = 1;
omap3_power_states[OMAP3_STATE_C3].type = OMAP3_STATE_C3;
omap3_power_states[OMAP3_STATE_C3].sleep_latency = 1500;
omap3_power_states[OMAP3_STATE_C3].wakeup_latency = 1800;
@@ -849,6 +832,8 @@ int omap3_idle_init(void)
state->flags = cx->flags;
state->enter = (state->flags & CPUIDLE_FLAG_CHECK_BM) ?
omap3_enter_idle_bm : omap3_enter_idle;
+ if (cx->type == OMAP3_STATE_C1)
+ dev->safe_state = state;
sprintf(state->name, "C%d", count+1);
count++;
}
diff -purN img/2.6_kernel/drivers/serial/8250.c 2.6_kernel/drivers/serial/8250.c
--- img/2.6_kernel/drivers/serial/8250.c 2008-05-09 18:50:53.000000000 -0500
+++ 2.6_kernel/drivers/serial/8250.c 2008-06-03 19:44:24.000000000 -0500
@@ -1221,6 +1221,14 @@ static inline void __stop_tx(struct uart
p->ier &= ~UART_IER_THRI;
serial_out(p, UART_IER, p->ier);
}
+#ifdef CONFIG_OMAP3_PM
+ {
+ /* Advertise partial idle to save power. RX side can do async wake */
+ unsigned int tmp;
+ tmp = (serial_in(p, UART_OMAP_SYSC) & 0x7) | (2 << 3);
+ serial_out(p, UART_OMAP_SYSC, tmp); /* smart-idle */
+ }
+#endif
}
static void serial8250_stop_tx(struct uart_port *port)
@@ -1268,6 +1276,15 @@ static void serial8250_start_tx(struct u
up->acr &= ~UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
+#ifdef CONFIG_OMAP3_PM
+ {
+ /* Don't advertise partial idle else TX irqs will not be seen */
+ /* Alternative is to set kernel timer at fifo drain rate */
+ unsigned int tmp;
+ tmp = (serial_in(up, UART_OMAP_SYSC) & 0x7) | (1 << 3);
+ serial_out(up, UART_OMAP_SYSC, tmp); /* no-idle */
+ }
+#endif
}
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