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From: Rolf Theunissen <rolf.theunissen@gmail.com>
To: alsa-devel@alsa-project.org
Subject: Hardware events
Date: Mon, 29 Nov 2010 12:54:43 +0100	[thread overview]
Message-ID: <4CF39483.4050704@gmail.com> (raw)

Hello,

For some hardware devices (for instance the ThinkPad EC) the volume can 
be changed by (only) hardware buttons. Changes in the the hardware 
mixers are notified in the driver via the function "snd_ctl_notify" with 
the mask SNDRV_CLT_EVENT_MASK_VALUE.
For notification of volume changes to the users of the system, an OSD 
can be used. To implement such a OSD, it must be possible to respond to 
changes done by the hardware.

This raises the following question: is it possible to detect the events 
originating from the hardware in the functions that handle the callbacks 
(set via snd_mixer_elem_set_callback/snd_hctl_elem_set_callback)? This 
would allow to implement an OSD that only responds to the hardware 
buttons and that would ignore events originating from "software".

Thanks

             reply	other threads:[~2010-11-29 11:54 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-29 11:54 Rolf Theunissen [this message]
2010-11-30  8:08 ` Hardware events Clemens Ladisch
2010-11-30 11:48   ` Rolf Theunissen
2010-12-02  7:51     ` Clemens Ladisch

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