noise from Dell laptops

noise from Dell laptops

[Len Brown]

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Do people with Dell laptops that are make noise in idle
find that Jos's patch along with acpi_cstate_limit=2
makes it quiet?

thanks,
-Len

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--- /usr/src/linux/drivers/acpi/processor.c	2004-08-07 18:25:15.064497551 +0200
+++ processor.c	2004-08-07 18:31:24.013809421 +0200
@@ -30,6 +30,14 @@
  *	4. Need C1 timing -- must modify kernel (IRQ handler) to get this.
  */
 
+/*
+ * 07/08/04; Jos Delbar <jos.delbar-Cru1EgDzd7c@public.gmane.org>:
+ * Recognize power state limit as a boot parameter.
+ *
+ * 31/07/04; Jos Delbar <jos.delbar-Cru1EgDzd7c@public.gmane.org>:
+ * Add user-definable processor power state limit.
+ */
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -80,6 +88,16 @@
 MODULE_DESCRIPTION(ACPI_PROCESSOR_DRIVER_NAME);
 MODULE_LICENSE("GPL");
 
+/*
+ * The acpi_cstate_limit module parameter represents the maximum processor power state or
+ * C state to promote to. Values of 1, 2 and 3 are equivalent to the C1, C2 and C3 sleep
+ * states, respectively. A value of 0 disables processor power management altogether.
+ */
+
+static int acpi_cstate_limit = ACPI_C_STATES_MAX;
+
+module_param(acpi_cstate_limit, int, S_IRUSR | S_IRGRP | S_IROTH);
+MODULE_PARM_DESC(acpi_cstate_limit, "Limit the processor power state (0 = disable power management)");
 
 static int acpi_processor_add (struct acpi_device *device);
 static int acpi_processor_remove (struct acpi_device *device, int type);
@@ -449,6 +467,7 @@
 		sleep_ticks = ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;
 		break;
 
+	case ACPI_STATE_C0:
 	default:
 		local_irq_enable();
 		return;
@@ -535,7 +554,7 @@
 	 * C0/C1
 	 * -----
 	 */
-	pr->power.state = ACPI_STATE_C1;
+	pr->power.state = (acpi_cstate_limit != ACPI_STATE_C0 ? ACPI_STATE_C1 : ACPI_STATE_C0);
 	pr->power.default_state = ACPI_STATE_C1;
 
 	/*
@@ -554,7 +573,7 @@
 	 * TBD: Demote to default C-State after long periods of activity.
 	 * TBD: Investigate policy's use of CPU utilization -vs- sleep duration.
 	 */
-	if (pr->power.states[ACPI_STATE_C2].valid) {
+	if (pr->power.states[ACPI_STATE_C2].valid && (acpi_cstate_limit >= ACPI_STATE_C2)) {
 		pr->power.states[ACPI_STATE_C1].promotion.threshold.count = 10;
 		pr->power.states[ACPI_STATE_C1].promotion.threshold.ticks =
 			pr->power.states[ACPI_STATE_C2].latency_ticks;
@@ -575,7 +594,7 @@
 	 * short or whenever bus mastering activity occurs.
 	 */
 	if ((pr->power.states[ACPI_STATE_C2].valid) &&
-		(pr->power.states[ACPI_STATE_C3].valid)) {
+		(pr->power.states[ACPI_STATE_C3].valid) && (acpi_cstate_limit >= ACPI_STATE_C3)) {
 		pr->power.states[ACPI_STATE_C2].promotion.threshold.count = 4;
 		pr->power.states[ACPI_STATE_C2].promotion.threshold.ticks =
 			pr->power.states[ACPI_STATE_C3].latency_ticks;
@@ -1859,10 +1878,15 @@
 		goto end;
 
 	seq_printf(seq, "active state:            C%d\n"
-			"default state:           C%d\n"
-			"bus master activity:     %08x\n",
+			"default state:           C%d\n",
 			pr->power.state,
-			pr->power.default_state,
+			pr->power.default_state);
+
+	if (acpi_cstate_limit < ACPI_C_STATES_MAX) seq_printf(seq,
+			"user limit:              C%d\n",
+			acpi_cstate_limit);
+
+	seq_printf(seq, "bus master activity:     %08x\n",
 			pr->power.bm_activity);
 
 	seq_puts(seq, "states:\n");
@@ -1876,6 +1900,11 @@
 			continue;
 		}
 
+		if (i > acpi_cstate_limit) {
+			seq_puts(seq, "<disabled>\n");
+			continue;
+		}
+
 		if (pr->power.states[i].promotion.state)
 			seq_printf(seq, "promotion[C%d] ",
 				pr->power.states[i].promotion.state);
@@ -2384,7 +2413,7 @@
 	
 	printk(KERN_INFO PREFIX "%s [%s] (supports",
 		acpi_device_name(device), acpi_device_bid(device));
-	for (i=1; i<ACPI_C_STATE_COUNT; i++)
+	for (i=0; i<=acpi_cstate_limit; i++)
 		if (pr->power.states[i].valid)
 			printk(" C%d", i);
 	if (pr->flags.throttling)
@@ -2417,7 +2446,7 @@
 	pr = (struct acpi_processor *) acpi_driver_data(device);
 
 	/* Unregister the idle handler when processor #0 is removed. */
-	if (pr->id == 0)
+	if ((pr->id == 0) && (pr->flags.power))
 		pm_idle = pm_idle_save;
 
 	status = acpi_remove_notify_handler(pr->handle, ACPI_DEVICE_NOTIFY, 
@@ -2447,6 +2476,10 @@
 	memset(&processors, 0, sizeof(processors));
 	memset(&errata, 0, sizeof(errata));
 
+	/* Check for illegal user limits. */
+	if(acpi_cstate_limit < ACPI_STATE_C0 || acpi_cstate_limit > ACPI_C_STATES_MAX)
+		return_VALUE(-EINVAL);
+
 	acpi_processor_dir = proc_mkdir(ACPI_PROCESSOR_CLASS, acpi_root_dir);
 	if (!acpi_processor_dir)
 		return_VALUE(-ENODEV);

Re: noise from Dell laptops

[Ow Mun Heng]

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Re: noise from Dell laptops

[Stefan Seyfried]

On Mon, Aug 09, 2004 at 01:14:34PM -0400, Len Brown wrote:
> Do people with Dell laptops that are make noise in idle
> find that Jos's patch along with acpi_cstate_limit=2
> makes it quiet?

my D600 does not buzz even when using C3, but since apparently there are
still some device drivers around which have problems with C3, this option
may be of use for other people, too.
-- 
Stefan Seyfried



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Re: noise from Dell laptops

[Jos Delbar]

>  Do people with Dell laptops that are make noise in idle
>  find that Jos"s patch along with acpi_cstate_limit=2
>  makes it quiet?
>  
>  thanks,
>  -Len

On my Dell Inspiron 500m the buzzing noise only disappears when limiting to C1 
(acpi_cstate_limit=1). Limiting to C2 does not seem to make a noticeable 
difference.

- Jos


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