# thinkpad_acpi on the T400

## w1n73rmu7e

Hi,

Has anyone used the ThinkPad ACPI kernel module with the T400? The site doesn't say whether it's compatible, and the Gentoo Power Management Guide says it could harm the hardware. Does anyone know whether it's safe or not? All I want to do is auto-dim/undim the screen when the AC power is disconnected/connected.

Thanks!

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## d2_racing

I use the module ACPI thinkpad inside the kernel and it's working pretty well.

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## w1n73rmu7e

What model ThinkPad do you have?

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## d2_racing

I have a T60P and a T61.

I will test at work my T400 too.

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## toralf

At least my T400 works fine with kernel built-in ACPI / power / CPU / whatever management.

There are only 2 bugs I've opened: http://bugzilla.kernel.org/show_bug.cgi?id=15100 and http://bugzilla.kernel.org/show_bug.cgi?id=15401

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## Link31

 *toralf wrote:*   

> http://bugzilla.kernel.org/show_bug.cgi?id=15401

 

About the mute button not working with headphones, this was the case since at least 2.6.28, so I'm pretty sure it never worked before. It's probably hardwired into the sound chip itself. I didn't tested on other operating systems though.

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## toralf

 *Link31 wrote:*   

> It's probably hardwired into the sound chip itself. I didn't tested on other operating systems though.

 Well, I've a dual-boot system. Under Windows XP the button works - although not really reliable what's surprising me. But if I open the Windows XP Mixer window then the button works.

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## Link31

Are you sure it is actually muting the sound channel, and not just lowering to volume to zero ?

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## toralf

 *Link31 wrote:*   

> Are you sure it is actually muting the sound channel, and not just lowering to volume to zero ?

 It really mutes it (and as already stated out in the bug report) w/ 2.6.33-05070-g64ba992 it is now working under Linux too.

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