Quick, Quick, Slooow

Quick, Quick, Slooow

[Al Cutter]

Hi all,

	I've just started playing around with this acpi business, but the
	processor performance (echo 1 > /proc/acpi/.../performance) didn't seem
	to work on my Sony SRX41P, it'd timeout in 
	acpi_processor_set_performance() ("Transition failed"). 

	The cpufreq interface seems to work fine however, so I made a little 
	patch against acpi-20021101 on 2.5.45 which makes :
		* acpi_processor_set_performance() call cpufreq to change the 
			clock speed, and
		* acpi_processor_write_performance() call ..._set_performance()

	Don't know if this makes sense, or it's just a kludge that gets around
	my particular problem, but it seems to work quite well with 
	autospeedstep (http://gpsdrive.kraftvoll.at/speedstep.shtml).

	Another thing I noticed is that osl.c seems to need linux/smp_lock.h
	to be included otherwise the kernel won't link if you're compiling
	for uni-proc due to missing kernel_locked().

 	Hope this is helpful.
	
	Al.

--------8<------- Patch -------8<----------

	
--- linux-2.5.45/drivers/acpi/processor.c.orig	Mon Nov  4 21:39:16 2002
+++ linux-2.5.45/drivers/acpi/processor.c	Mon Nov  4 21:25:18 2002
@@ -1047,6 +1047,7 @@
 	u8			value = 0;
 	int			i = 0;
 	struct cpufreq_freqs    cpufreq_freqs;
+	struct cpufreq_policy   policy;
 
 	ACPI_FUNCTION_TRACE("acpi_processor_set_performance");
 
@@ -1078,59 +1079,13 @@
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Transitioning from P%d to P%d\n",
 		pr->performance.state, state));
 
-	/* cpufreq frequency struct */
-	cpufreq_freqs.cpu = pr->id;
-	cpufreq_freqs.old = pr->performance.states[pr->performance.state].core_frequency;
-	cpufreq_freqs.new = pr->performance.states[state].core_frequency;
-
-	/* notify cpufreq */
-	cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
-
-	/*
-	 * First we write the target state's 'control' value to the
-	 * control_register.
-	 */
-
-	port = pr->performance.control_register;
-	value = (u16) pr->performance.states[state].control;
-
-	ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
-		"Writing 0x%02x to port 0x%04x\n", value, port));
-
-	outb(value, port); 
-
-	/*
-	 * Then we read the 'status_register' and compare the value with the
-	 * target state's 'status' to make sure the transition was successful.
-	 * Note that we'll poll for up to 1ms (100 cycles of 10us) before
-	 * giving up.
-	 */
+	cpufreq_get_policy(&policy, pr->id);
 
-	port = pr->performance.status_register;
+	policy.cpu = pr->id;
+	policy.max = pr->performance.states[state].core_frequency * 1000;
 
-	ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
-		"Looking for 0x%02x from port 0x%04x\n",
-		(u8) pr->performance.states[state].status, port));
+	cpufreq_set_policy(&policy);
 
-	for (i=0; i<100; i++) {
-		value = inb(port);
-		if (value == (u8) pr->performance.states[state].status)
-			break;
-		udelay(10);
-	}
-
-	/* notify cpufreq */
-	cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
-
-	if (value != pr->performance.states[state].status) {
-		unsigned int tmp = cpufreq_freqs.new;
-		cpufreq_freqs.new = cpufreq_freqs.old;
-		cpufreq_freqs.old = tmp;
-		cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
-		cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
-		ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Transition failed\n"));
-		return_VALUE(-ENODEV);
-	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
 		"Transition successful after %d microseconds\n",
@@ -1772,7 +1727,7 @@
 
 	/* test if it works */
 	current_state = pr->performance.state;
-/*
+
 	if (current_state == pr->limit.state.px) {
 		result = acpi_processor_set_performance(pr, (pr->performance.state_count - 1));
 		if (result) {
@@ -1797,7 +1752,7 @@
 			return_VALUE(-ENODEV);
 		}
 	}
-*/
+
 	/* initialization of main "cpufreq" code*/
 	driver = kmalloc(sizeof(struct cpufreq_driver) + 
 			 NR_CPUS * sizeof(struct cpufreq_policy), GFP_KERNEL);
@@ -2020,6 +1975,7 @@
 
 	ACPI_FUNCTION_TRACE("acpi_processor_read_performance");
 
+
 	if (!pr || (off != 0))
 		goto end;
 
@@ -2077,13 +2033,15 @@
 	
 	state_string[count] = '\0';
 	new_state = simple_strtoul(state_string, NULL, 0);
-
+/*
 	cpufreq_get_policy(&policy, pr->id);
 
 	policy.cpu = pr->id;
 	policy.max = pr->performance.states[new_state].core_frequency * 1000;
 
 	result = cpufreq_set_policy(&policy);
+*/
+	result = acpi_processor_set_performance(pr,new_state);
 	if (result)
 		return_VALUE(result);
 
@@ -2289,6 +2247,7 @@
 
 	ACPI_FUNCTION_TRACE("acpi_processor_add_fs");
 
+
 	if (!acpi_processor_dir) {
 		acpi_processor_dir = proc_mkdir(ACPI_PROCESSOR_CLASS, 
 			acpi_root_dir);


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Re: Quick, Quick, Slooow

[Dominik Brodowski]

Hi Al,

On Tue, Nov 05, 2002 at 12:13:59AM +0000, Al Cutter wrote:
> 	I've just started playing around with this acpi business, but the
> 	processor performance (echo 1 > /proc/acpi/.../performance) didn't seem
> 	to work on my Sony SRX41P, it'd timeout in 
> 	acpi_processor_set_performance() ("Transition failed"). 
> 
> 	The cpufreq interface seems to work fine however, so I made a little 
> 	patch against acpi-20021101 on 2.5.45 which makes :
> 		* acpi_processor_set_performance() call cpufreq to change the 
> 			clock speed, and
> 		* acpi_processor_write_performance() call ..._set_performance()
> 
> 	Don't know if this makes sense, or it's just a kludge that gets around
> 	my particular problem, but it seems to work quite well with 
> 	autospeedstep (http://gpsdrive.kraftvoll.at/speedstep.shtml).
Actually, this would be the wrong way 'round:

There are several "techniques" to switch the performance states / the CPU
freuqency. One is ACPI, others are "legacy" interfaces for Intel SpeedStep,
AMD PowerNow, Cyrix Longhaul, Transmeta Crusoe, ... 

cpufreq offers an unified interface for all these drivers (and a bit
more...) - and so you shouldn't even recognize from reading this interface,
/proc/cpufreq, what cpufreq driver (ACPI, SpeedStep, etc.) is used. 

Your patch would actually remove the ACPI cpufreq driver. Additionally,
you shouldn't try to use the ACPI generic interface to access a general
CPUfreq driver; but use /proc/cpufreq [or /proc/sys/cpu/0/] directly.

	Dominik


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Re: Quick, Quick, Slooow

[Al Cutter]

On Tue, Nov 05, 2002 at 09:43:34AM +0100, Dominik Brodowski wrote:
> Actually, this would be the wrong way 'round:
> 
> There are several "techniques" to switch the performance states / the CPU
> freuqency. One is ACPI, others are "legacy" interfaces for Intel SpeedStep,
> AMD PowerNow, Cyrix Longhaul, Transmeta Crusoe, ... 
> 
> cpufreq offers an unified interface for all these drivers (and a bit
> more...) - and so you shouldn't even recognize from reading this interface,
> /proc/cpufreq, what cpufreq driver (ACPI, SpeedStep, etc.) is used. 
> 
> Your patch would actually remove the ACPI cpufreq driver. Additionally,
> you shouldn't try to use the ACPI generic interface to access a general
> CPUfreq driver; but use /proc/cpufreq [or /proc/sys/cpu/0/] directly.
> 
> 	Dominik

Whoops, must pay more attention !

Thanks for explaining.

	Al


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Re: Quick, Quick, Slooow

[Al Cutter]

On Tue, Nov 05, 2002 at 10:20:37AM +0000, Alan Cox wrote:
> The legacy interfaces seem to have become favoured again by Windows at
> least and called "native power management" 8)

As opposed to my "naive power management" :)




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Re: Quick, Quick, Slooow

[Alan Cox]

> There are several "techniques" to switch the performance states / the CPU
> freuqency. One is ACPI, others are "legacy" interfaces for Intel SpeedStep,
> AMD PowerNow, Cyrix Longhaul, Transmeta Crusoe, ... 

The legacy interfaces seem to have become favoured again by Windows at
least and called "native power management" 8)

> 
>


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