[alsa-devel] [PATCH 0/4] ALSA: hda beep clean up

Jaroslav Kysela perex at perex.cz
Wed Jul 4 09:43:23 CEST 2012

Date 4.7.2012 07:16, Takashi Iwai wrote:
> At Tue, 03 Jul 2012 22:01:45 +0200,
> Jaroslav Kysela wrote:
>> Date 3.7.2012 18:31, Jaroslav Kysela wrote:
>>> Date 3.7.2012 18:03, Takashi Iwai wrote:
>>>> Hi,
>>>> this is a series of small cleanups of HD-audio beep code.
>>>> Since the keyboard driver already handles the simultaneous outputs
>>>> from the multiple input beep instances, there is no merit to have
>>>> beep_mode=2 option to switch the beep input device.
>>> Acked-by: Jaroslav Kysela <perex at perex.cz>
>> While I acked this, I vaguely remember now, that the event duplication
>> (simultaneous outputs) caused some issues on some Lenovo notebooks.
>> When the pcspkr and HDA beep generator is connected to the same output
>> (integrated speakers), it may cause some issues (bad beep quality -
>> frequency etc.).
>> I looked to the input code, and the kd_mksound() calls
>> input_handler_for_each_handle(), thus the event is duplicated to all
>> beep generators, right?
> Right.
>> The beep_mode=2 was introduced to let users to help with this issue with
>> a comfortable way.
> Not really.  At the time this was introduced, the keyboard driver took
> only a single input handle exclusively, namely only the last
> registered one.  Thus playing on both had never happened until
> recently.

OK, thanks for the clarification. The question is, if it's the desired
behaviour. Multiple outs can cause some harmonic effects. It would be
nice, if the input layer can turn on/off (filter) the beep events at
runtime separately for all registered drivers. The setup can be handled
using sysfs or so..


Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project; Red Hat, Inc.

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