[alsa-devel] [PATCH 1/5] HDA : patch_sigmatel.c : cleanups

[Takashi Iwai]

At Sat, 1 Sep 2007 11:11:24 +0300,
Maxim Levitsky wrote:
> 
> On Friday 31 August 2007 13:56:19 Takashi Iwai wrote:
> > At Tue, 28 Aug 2007 12:46:01 +0200,
> > I wrote:
> > > 
> > > At Tue, 28 Aug 2007 05:07:48 +0300,
> > > Maxim Levitsky wrote:
> > > > 
> > > > From c9392b0293f7d39e40e4a5e07e7b140d5a385079 Mon Sep 17 00:00:00 2001
> > > > From: Maxim Levitsky <maximlevitsky at gmail.com>
> > > > Date: Mon, 27 Aug 2007 22:49:49 +0300
> > > > Subject: [PATCH] HDA : patch_sigmatel.c : cleanups
> > > 
> > > OK, it's a nice clean-up.  Can be merged as is.
> > 
> > Now merged to ALSA HG tree.
> > 
> > If the fixes for other patches are ready, please let me know.
> > I'll merge them to HG tree, too.
> > 
> > 
> > Thanks,
> > 
> > Takashi
> > 
> 
> 
> Hi,
> 
> I run into unexpected problems:
> latest hg adds a power saving mode to hda codec, and while the idea is nice, it plays very bad with my patches.
> 
> 1) The analog loop-back becomes a nightmare, since power-saving code turns the codec off, but for loopback to function it has to be powered.
> I tried to add a snd_hda_power_up/down calls to .put function, and while it did stop the unwanted powerdown of codec, on resume from ram , analog loopback vanishes.
> any access to device (arecord/aplay or any mixer change make analog loop work again).
> Can you tell me how I properly tell the core that user _uses_ the device, and device should be powered.
> 
> 2) on resume all playback apps hang, and recording (arecord) exits with message "Resource temporary unavailable"
> restarting apps help.

First, you need to use snd_hda_codec_write_cache() for values to be
resumed, especially in control put callbacks.  The amp values accessed
via snd_hda_codec_amp_update() are always cached, but
snd_hda_codec_write() doesn't cache.

The second thing is analog-loopback.  The driver should keep the power
when the analog-loopback is on, and enables power-saving again when
it's off.  So far, I thought only the amp controls, but now it's a
different one.

In this case, the put callback would need to call snd_hda_pwoer_up()
and snd_hda_power_down() appropriately to turn on/off power-save.
They should be called only at transition.  Namely, when 0->1
transition of spec->aloopback occurs in put callback, it calls
snd_hda_power_up().  When 1->0 occurs, call snd_hda_power_down().


Takashi