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SkyMeadow 06-12-2012 06:27 PM

Volume control display and media control keys Linux Mint 12 - Thinkpad R52
We have been running Linux Mint 12 on a Lenovo ThinkPad R52 for several months. We installed the multimedia codecs. Initially we had problems playing DVDs on this laptop but by switching to a different media player we were able to play DVDs without any problems.

There is a lack of coordination between the volume control widget on the upper line of the GNOME classic desktop, and the media control keys on the keyboard. Visual feedback is missing when you control the audio system by pressing a media control key on the keyboard.

The volume control widget displays the current audio volume correctly, and the audio level can be changed by moving the slider. This is true both for the GNOME classic widget (a vertical slider), the GNOME widget (a horizontal slider), and the Sound Preferences (horizontal slider).

The volume up, volume down, and mute buttons on the keyboard all work and are mapped to the correct audio functions. E.g. the "Audio mute" button is mapped to the "Volume mute" function and causes the sound to be muted. We ascertained the mappings using System Settings, Keyboard, Sounds and Media ... although it does not tell us what piece of code is performing the functions.

However when the media control keys are used, the volume widget at the top of the desktop does not change. It does not indicate that the sound is muted, or that the audio volume has been raised or lowered.

In other words, the audio on-screen display widget is not coordinated with the media control keys.

//* I don't know if this symptom is related: if we use a Java application that has audio, we cannot play a youtube video in the Firefox browser simultaneously. It seems that one application grabs exclusive control of the audio and applications are not sharing control as they did in Windows. I wonder if this indicates some kind of error in the way we have the audio set up. *//

List PCI devices command lspci returns:
00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 03)

uname -r returns kernel information:

I also issued the dmesg command and an 80K file was produced that is interesting but I'm not sure which part(s) of it to post here if any. I will study it offline looking for any clues about the audio hardware.

I don't know how to proceed to debug this.

(Note that Linux Mint 12 audio control works perfectly on my other ThinkPad which is a T60p.)

Hope somebody can point me in the right direction.

Thank you.
"Sky Meadow"

Didier Spaier 06-14-2012 03:41 AM

First, congratulations for the precise statement of the problem you want to solve. As we say "un problème bien posé est déjà à demi résolu".

It seems that the behavior of the sound system be different between different generations of Thinkpad.

This is not very surprising, as there have been a lot of changes in events processing (among which, those related to sound) during Thinkpad history.

You could find useful information to investigate further on the ThinkWiki web site and its Thinkpad-acpi page.

The document included in the kernel source /usr/src/linux<version>/Documentation/laptops/thinkpad-acpi.txt is worth reading too.

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