Quite a few HDA (and other sound cards) are known to make faint "plopp" or other noises when powering down/up. For some cards these noises can be suppressed in software, however for others this appears not to be possible (according to some HDA driver devs at least, as discussed a Plumbers conf). It would be nice if we could have a blacklist in the kernel that makes sure power saving is only enabled for those where this plopp sound is known to not exist.
As a side note: OpenSuse disables all power management for sound cards on power plug/unplug via a script in/usr/lib/pm-utils/power.d/sound-pm. mjg59 thinks this is not a good idea we should follow, saying that what isn't acceptable in AC mode isn't acceptable in battery mode either. And I guess I agree.
But where is that list? Every release we try to enable the power savings and each time we end up disabling it.
Also, I've got a machine that turns the speaker LED orange to indicated the sound is muted.... and that happens when we turn off the power to the card even though we're not really muted.
This bug appears to have been reported against 'rawhide' during the Fedora 12 development cycle.
Changing version to '12'.
More information and reason for this action is here:
I would prefer an user space solution for this problem. Any default behaviour is not ideal in this case, because:
a) if this function is off - it might be obsolete with new HDA driver code
b) if this function is on - cracks on hw on/off
Perhaps, a mixer control like "Power Save" might be introduced, so users can touch this behaviour in a GUI.
(In reply to comment #4)
> Perhaps, a mixer control like "Power Save" might be introduced, so users can
> touch this behaviour in a GUI.
Uh, I dont think forwarding this problem to the user really brings us forward.
We could add a couple of rules for this udev. I am pretty sure I can convince Kay to accept rules into udev for this, although this looks a like a lot of work to maintain...
Alternatively this could be maintained as part of the alsa mixer init db?
*** Bug 548123 has been marked as a duplicate of this bug. ***
*** Bug 539304 has been marked as a duplicate of this bug. ***
This issue is listed as one of the Common F12 bugs:
In the absence of a list of known good/bad models we really should default to the safe choice (e.g. disable powersaving).
echo 0 > /sys/module/snd_hda_intel/parameters/power_save first helped but when I change volume sound crackling again! only volume at %100 no crackling. Any clue ?
F13 Beta Blocker criterion 14 says: "In most cases, the installed system must be able to play back sound with gstreamer-based applications". This bug isn't exactly "sound doesn't work at all" but it is listed on Common Bugs and is apparently fairly visible. Nominating as F13Target.
Since kernel builds around 220.127.116.11 HDA powersaving has been disabled by default (CONFIG_SND_HDA_POWER_SAVE_DEFAULT=0) in both F-12 and devel branches.
SND_HDA powersaving defaults can be changed for kernels in current (F16+) releases (looks like no plopp sounds here)?