[pulseaudio-discuss] [PATCH] sink/source: Fix restore of volume on devices without hw volume

[Tanu Kaskinen]

On Tue, 2014-08-26 at 13:54 +0200, David Henningsson wrote:
> Module-device-restore sets real_volume, but soft_volume remains at
> max, so if a device only has soft_volume (i e no hw volume controls),
> its volume was not restored correctly.

module-device-restore deals with the sink reference volume only, so I
think the wording of the commit message should be improved. Claiming
that module-device-restore sets the real volume confused me a bit
(making me think initially the patch was totally misguided). It's true
that the real volume is always initialized directly from reference
volume, however.

> 
> Reported-by: Richardo Salveti de Araujo <ricardo.salveti at canonical.com>
> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> ---
> 
> Note: I haven't looked in detail what happens if the hw steps are coarse,
> so we need to set both soft_volume and reference_volume from real_volume.
> So it's possible this is just a bandaid.

I don't know why the steps being coarse would have any effect on the
logic - if there's hw volume, it will anyway be too coarse to be used
without software compensation (assuming that there's dB information -
otherwise soft_volume should always be at max anyway).

I had a look, and if alsa provides dB information, alsa-sink.c will take
care of initializing real_volume and soft_volume correctly (btw, I think
it would be better if alsa-sink.c didn't directly manipulate real_volume
and soft_volume, but that's another discussion). sink.c will then update
reference_volume correctly in pa_sink_put(), so this case works fine. If
alsa doesn't provide dB information, alsa-sink.c will initialize
real_volume correctly and leave soft_volume alone (should be at max all
the time when there's no dB information), so this works too.

The patch looks good to me, except for the commit message.

-- 
Tanu