[PATHC] Relaxed syntax for the processor PBLK length

[PATHC] Relaxed syntax for the processor PBLK length

[Eric Piel]

[-- Attachment #1: Type: text/plain, Size: 722 bytes --]

Hello,

In the original DSDT of my laptop (Acer TravelMate 614) the processor 
PBLK length is declared to be 5. The legal and only allowed value is 6. 
This is an error in the DSDT and actually it is 6. Allowing Linux ACPI 
to read also processor PBLK length of 5 works and permits the processor 
to have the C-states correctly detected. In turn it allows the processor 
to get less hot (so this is eventually useful).

I've noticed that some other Acer DSDT also have this length 
mis-indicated. The attached patch adds some logic to the ACPI to allow a 
processor PBLK length of 5 when the syntax is relaxed.

Hoping this can be useful,
Eric

Signed-off-by: Eric Piel <eric.piel-VkQ1JFuSMpfAbQlEx87xDw@public.gmane.org>

[-- Attachment #2: acpi-processor-pblk-length-2.6.11-rc2.patch --]
[-- Type: text/x-patch, Size: 993 bytes --]

--- linux-2.6.11-rc2/drivers/acpi/processor_core.c.orig	2005-01-23 01:24:55.315650055 +0100
+++ linux-2.6.11-rc2/drivers/acpi/processor_core.c	2005-01-23 01:27:32.016020121 +0100
@@ -492,9 +492,16 @@ acpi_processor_get_info (
 	if (!object.processor.pblk_address)
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
 	else if (object.processor.pblk_length != 6)
-		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid PBLK length [%d]\n",
-			object.processor.pblk_length));
-	else {
+		if (object.processor.pblk_length == 5 && !acpi_strict) {
+			printk(KERN_INFO PREFIX 
+				"PBLK length is 5 instead of 6, concidering "
+				"it is good anyway.\n");
+			goto PBLK_length_good;
+		} else
+			ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid PBLK length [%d]\n",
+				object.processor.pblk_length));
+ 	else {
+PBLK_length_good:
 		pr->throttling.address = object.processor.pblk_address;
 		pr->throttling.duty_offset = acpi_fadt.duty_offset;
 		pr->throttling.duty_width = acpi_fadt.duty_width;

Re: [PATHC] Relaxed syntax for the processor PBLK length

[Johan Vromans]

Eric Piel <Eric.Piel-VkQ1JFuSMpfAbQlEx87xDw@public.gmane.org> writes:

> In the original DSDT of my laptop (Acer TravelMate 614) the processor
> PBLK length is declared to be 5. The legal and only allowed value is
> 6. This is an error in the DSDT and actually it is 6. Allowing Linux
> ACPI to read also processor PBLK length of 5 works and permits the
> processor to have the C-states correctly detected. In turn it allows
> the processor to get less hot (so this is eventually useful).

Wouldn't it be better to correct this in the DSDT itself?

-- Johan


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Richard Dawe]

Hello.

Eric Piel wrote:
[snip]
> --- linux-2.6.11-rc2/drivers/acpi/processor_core.c.orig	2005-01-23 01:24:55.315650055 +0100
> +++ linux-2.6.11-rc2/drivers/acpi/processor_core.c	2005-01-23 01:27:32.016020121 +0100
> @@ -492,9 +492,16 @@ acpi_processor_get_info (
>  	if (!object.processor.pblk_address)
>  		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
>  	else if (object.processor.pblk_length != 6)
> -		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid PBLK length [%d]\n",
> -			object.processor.pblk_length));
> -	else {
> +		if (object.processor.pblk_length == 5 && !acpi_strict) {
> +			printk(KERN_INFO PREFIX 
> +				"PBLK length is 5 instead of 6, concidering "
> +				"it is good anyway.\n");
[snip]

Typo: concidering -> considering

Bye, Rich =]

-- 
Richard Dawe [ http://homepages.nildram.co.uk/~phekda/richdawe/ ]

"You can't evaluate a man by logic alone."
   -- McCoy, "I, Mudd", Star Trek


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Bruno Ducrot]

On Sun, Jan 30, 2005 at 09:05:22PM +0100, Eric Piel wrote:
> Hello,
> 
> In the original DSDT of my laptop (Acer TravelMate 614) the processor 
> PBLK length is declared to be 5. The legal and only allowed value is 6. 
> This is an error in the DSDT and actually it is 6. Allowing Linux ACPI 
> to read also processor PBLK length of 5 works and permits the processor 
> to have the C-states correctly detected. In turn it allows the processor 
> to get less hot (so this is eventually useful).
> 
> I've noticed that some other Acer DSDT also have this length 
> mis-indicated. The attached patch adds some logic to the ACPI to allow a 
> processor PBLK length of 5 when the syntax is relaxed.
> 

You should consider to disable C3 in this case IMHO.

Thanks,

-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Eric Piel]

Bruno Ducrot a écrit :
> On Sun, Jan 30, 2005 at 09:05:22PM +0100, Eric Piel wrote:
> 
>>Hello,
>>
>>In the original DSDT of my laptop (Acer TravelMate 614) the processor 
>>PBLK length is declared to be 5. The legal and only allowed value is 6. 
>>This is an error in the DSDT and actually it is 6. Allowing Linux ACPI 
>>to read also processor PBLK length of 5 works and permits the processor 
>>to have the C-states correctly detected. In turn it allows the processor 
>>to get less hot (so this is eventually useful).
>>
>>I've noticed that some other Acer DSDT also have this length 
>>mis-indicated. The attached patch adds some logic to the ACPI to allow a 
>>processor PBLK length of 5 when the syntax is relaxed.
>>
> 
> 
> You should consider to disable C3 in this case IMHO.
Why? Actually this patch is especially designed to allow C3 state to be 
used on my computer. This works for more than 6 months without any 
appearent problem, is there anything I'm not aware of?

Eric


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Bruno Ducrot]

On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> Why? Actually this patch is especially designed to allow C3 state to be 
> used on my computer. This works for more than 6 months without any 
> appearent problem, is there anything I'm not aware of?

I thought some BIOS devellopers wanted to use a size for the
pblk of 5 just to not allow C3 (which correspond to the sixth io
register).

I'm not alone to think this.

Nate: FreeBSD allow only C2 in this case.  What do you think about this
report?
Do you have an example of some kind of malfunction when enabling C3?

-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Eric Piel]

Bruno Ducrot a écrit :
> On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> 
>>Why? Actually this patch is especially designed to allow C3 state to be 
>>used on my computer. This works for more than 6 months without any 
>>appearent problem, is there anything I'm not aware of?
> 
> 
> I thought some BIOS devellopers wanted to use a size for the
> pblk of 5 just to not allow C3 (which correspond to the sixth io
> register).
> 
> I'm not alone to think this.
> 
> Nate: FreeBSD allow only C2 in this case.  What do you think about this
> report?
> Do you have an example of some kind of malfunction when enabling C3?

Actually in the DSDT the C2 seems really deactivated (latency is set to 
the maximum, something like 999 ms) while C3 has a declared latency that 
seems realistic. Additionally, in the C3 state, the computer works 
perfectly.

Is there anyway in Windows to check if it uses a particular C state?

Eric


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Herman Sheremetyev]

A length other than 6 used to disable PBLK may also indicate that C 
states are implemented using _CST methods instead of the Processor 
structure.  At least that's how it is on Asus M6N series, PBLK length is 
set to 7, and there are some other clues in the FADT latency settings to 
indicate that the BIOS writers didn't want this info used.

-Herman

Bruno Ducrot wrote:
> On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> 
>>Why? Actually this patch is especially designed to allow C3 state to be 
>>used on my computer. This works for more than 6 months without any 
>>appearent problem, is there anything I'm not aware of?
> 
> 
> I thought some BIOS devellopers wanted to use a size for the
> pblk of 5 just to not allow C3 (which correspond to the sixth io
> register).
> 
> I'm not alone to think this.
> 
> Nate: FreeBSD allow only C2 in this case.  What do you think about this
> report?
> Do you have an example of some kind of malfunction when enabling C3?
> 


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Dominik Brodowski]

On Mon, Jan 31, 2005 at 04:29:31PM +0100, Bruno Ducrot wrote:
> On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> > Why? Actually this patch is especially designed to allow C3 state to be 
> > used on my computer. This works for more than 6 months without any 
> > appearent problem, is there anything I'm not aware of?
> 
> I thought some BIOS devellopers wanted to use a size for the
> pblk of 5 just to not allow C3 (which correspond to the sixth io
> register).
> 
> I'm not alone to think this.
> 
> Nate: FreeBSD allow only C2 in this case.  What do you think about this
> report?
> Do you have an example of some kind of malfunction when enabling C3?

IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.

See also:
http://marc.theaimsgroup.com/?l=acpi4linux&m=104570606821625&w=2


	Dominik


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Eric Piel]

Dominik Brodowski a écrit :
> 
> IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.
> 
> See also:
> http://marc.theaimsgroup.com/?l=acpi4linux&m=104570606821625&w=2

Hummm, then I guess that my patch is not so welcome :-( Anyway, note 
that this patch allows a wrong PBLK length only if the syntax is 
relaxed. If your computer has a broken C2 state you could still force 
the strict syntax and it would boot.

Eric


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Dominik Brodowski]

On Mon, Jan 31, 2005 at 05:14:21PM +0100, Eric Piel wrote:
> Dominik Brodowski a écrit :
> >
> >IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.
> >
> >See also:
> >http://marc.theaimsgroup.com/?l=acpi4linux&m=104570606821625&w=2
> 
> Hummm, then I guess that my patch is not so welcome :-( Anyway, note 
> that this patch allows a wrong PBLK length only if the syntax is 
> relaxed. If your computer has a broken C2 state you could still force 
> the strict syntax and it would boot.

However, Len's message indicates that I wasn't the only one who complained
:-(

	Dominik


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Dominik Brodowski]

On Mon, Jan 31, 2005 at 05:26:28PM +0100, Dominik Brodowski wrote:
> On Mon, Jan 31, 2005 at 05:14:21PM +0100, Eric Piel wrote:
> > Dominik Brodowski a écrit :
> > >
> > >IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.
> > >
> > >See also:
> > >http://marc.theaimsgroup.com/?l=acpi4linux&m=104570606821625&w=2
> > 
> > Hummm, then I guess that my patch is not so welcome :-( Anyway, note 
> > that this patch allows a wrong PBLK length only if the syntax is 
> > relaxed. If your computer has a broken C2 state you could still force 
> > the strict syntax and it would boot.
> 
> However, Len's message indicates that I wasn't the only one who complained
> :-(

That should state "Andy's" instead of "Len's"... and random lockups are not
a nice thing to debug... So I'd prefer a command line or DMI option which allows
for C2 on broken syntax.

	Dominik


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Bruno Ducrot]

On Mon, Jan 31, 2005 at 04:59:17PM +0100, Dominik Brodowski wrote:
> On Mon, Jan 31, 2005 at 04:29:31PM +0100, Bruno Ducrot wrote:
> > On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> > > Why? Actually this patch is especially designed to allow C3 state to be 
> > > used on my computer. This works for more than 6 months without any 
> > > appearent problem, is there anything I'm not aware of?
> > 
> > I thought some BIOS devellopers wanted to use a size for the
> > pblk of 5 just to not allow C3 (which correspond to the sixth io
> > register).
> > 
> > I'm not alone to think this.
> > 
> > Nate: FreeBSD allow only C2 in this case.  What do you think about this
> > report?
> > Do you have an example of some kind of malfunction when enabling C3?
> 
> IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.
> 

Does your desktop support throttling?

-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.


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Re: [PATHC] Relaxed syntax for the processor PBLK length

[Dominik Brodowski]

On Mon, Jan 31, 2005 at 05:36:03PM +0100, Bruno Ducrot wrote:
> On Mon, Jan 31, 2005 at 04:59:17PM +0100, Dominik Brodowski wrote:
> > On Mon, Jan 31, 2005 at 04:29:31PM +0100, Bruno Ducrot wrote:
> > > On Mon, Jan 31, 2005 at 04:11:59PM +0100, Eric Piel wrote:
> > > > Why? Actually this patch is especially designed to allow C3 state to be 
> > > > used on my computer. This works for more than 6 months without any 
> > > > appearent problem, is there anything I'm not aware of?
> > > 
> > > I thought some BIOS devellopers wanted to use a size for the
> > > pblk of 5 just to not allow C3 (which correspond to the sixth io
> > > register).
> > > 
> > > I'm not alone to think this.
> > > 
> > > Nate: FreeBSD allow only C2 in this case.  What do you think about this
> > > report?
> > > Do you have an example of some kind of malfunction when enabling C3?
> > 
> > IIRC my desktop has a pblk of 5, and enabling _C2_ causes random lockups.
> > 
> 
> Does your desktop support throttling?

brodo@mondschein ~ $ cat /proc/acpi/processor/CPU0/throttling
<not supported>

:)
	Dominik


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