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From: Roel Kluin <>
To: Greg KH <>
Cc: Henrique de Moraes Holschuh <>,
	Roland Dreier <>,,,, lkml <>,
Subject: Re: [PATCH][drivers/misc/thinkpad_acpi.c] duplicate test if (level & TP_EC_FAN_FULLSPEED)
Date: Thu, 07 Feb 2008 00:48:24 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Greg KH wrote:
> On Tue, Feb 05, 2008 at 09:34:54AM +0100, Roel Kluin wrote:
>> Henrique de Moraes Holschuh wrote:
>>> On Tue, 05 Feb 2008, Roel Kluin wrote:
>>>> Roland Dreier wrote:

>>>>>  > Note the duplicate test 'if (level & TP_EC_FAN_FULLSPEED)'. should
>>>>>  > this be replaced by
>>>>> Actually I suspect one of the two tests should be against TP_EC_FAN_AUTO
>>>>> (based on the comment).
>>>> Thanks Roland, for your info

>>> ACK.  This needs to be sent to stable as well.  I think both 2.6.22 and
>>> 2.6.23 need this patch.
>> CC
> Please send us a real copy of the patch, when it goes into Linus's tree,
> so we know what to apply, and that it is safe to do so.

It's a oneliner and the patch is from linus' tree.
in commit eaa7571b2d1a08873e4bdd8e6db3431df61cd9ad, a safety net for TPEC
fan control mode was added. Quoting that patch:

"The Linux ThinkPad community is not positive that all ThinkPads that do
HFSP EC fan control do implement full-speed and auto modes, some of the
earlier ones supporting HFSP might not.

If the EC ignores the AUTO or FULL-SPEED bits, it will pay attention to the
lower three bits that set the fan level. And as thinkpad-acpi was leaving
these set to zero, it would stop(!) the fan, which is Not A Good Thing.
So, as a safety net, we now make sure to also set the fan level part of the
HFSP register to speed 7 for full-speed, and a minimum of speed 4 for auto

However, in the section below the test for the FULL-SPEED bits was not added:
the AUTO bits were tested twice. This patch corrects this and ensures that
the fan level part of the  HFSP register is set to a minimum of speed 4 for
auto mode.

Signed-off-by: Roel Kluin <>
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index cf56647..3c323fe 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -4138,7 +4138,7 @@ static int fan_set_level(int level)
 		 * or FULLSPEED mode bits and just ignore them */
 		if (level & TP_EC_FAN_FULLSPEED)
 			level |= 7;	/* safety min speed 7 */
-		else if (level & TP_EC_FAN_FULLSPEED)
+		else if (level & TP_EC_FAN_AUTO)
 			level |= 4;	/* safety min speed 4 */
 		if (!acpi_ec_write(fan_status_offset, level))

  reply	other threads:[~2008-02-06 23:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-04 22:07 [drivers/misc/thinkpad_acpi.c] " Roel Kluin
2008-02-04 22:13 ` Roland Dreier
2008-02-04 23:24   ` [PATCH][drivers/misc/thinkpad_acpi.c] " Roel Kluin
2008-02-05  5:05     ` Henrique de Moraes Holschuh
2008-02-05  8:34       ` Roel Kluin
2008-02-06 23:07         ` Greg KH
2008-02-06 23:48           ` Roel Kluin [this message]
2008-02-07  1:18             ` Henrique de Moraes Holschuh
2008-02-07  7:28               ` [stable] " Greg KH
2008-02-07  5:55             ` Greg KH
2008-02-07  6:17     ` Len Brown
  -- strict thread matches above, loose matches on Subject: below --
2008-02-04 21:59 [PATCH][drivers/misc/thinkpad_acpi.c] duplicate test 'if (level & TP_EC_FAN_FULLSPEED)' Roel kluin

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