Heads up: powerdown changes to alsa-base in Lucid/10.04

Amit Kucheria amit.kucheria at canonical.com
Tue Feb 16 11:55:35 UTC 2010

Incorrect alias when cc'ing the kernel mailing list.

----- Forwarded message from Amit Kucheria <amit.kucheria at canonical.com> -----

Date: Tue, 16 Feb 2010 13:31:05 +0200
From: Amit Kucheria <amit.kucheria at canonical.com>
To: Daniel Chen <seven.steps at gmail.com>
Cc: k-t at matterhorn.verdurent.com
Subject: Re: Heads up: powerdown changes to alsa-base in Lucid/10.04
User-Agent: Mutt/1.5.20 (2009-06-14)

Hi Daniel,

On 09 Dec 30, Daniel Chen wrote:
> Hi, folks,
> [a more complete version of my announcement in #ubuntu-devel on Freenode]
> Based on the abysmal feedback that we received for Karmic/9.10
> regarding powering down HDA controllers after ten idle seconds[0],

Do you have any statistics on how many machines were affected by these
changes? I see many bugs with 'HDA power_save=10' in their title but am
unable to comment on the mix of HW involved.  

What about codecs and amplifiers? Is there a pattern on which ones are most
affected or is it scattered all over the place?

> I've reverted the change in the most recent upload of alsa-driver
> to Lucid/10.04 and, in doing so, restored the behavior
> shipped in Jaunty/9.04. So, at the cost of less efficient battery use
> [for unplugged laptops] one will no longer hear the annoying crackling
> and popping associated with these HDA controllers.
> This change was also driven by the fact that Lucid's shipped kernel is
> highly unlikely to have the necessary patches backported. The good

Can you elaborate on what patches needed porting? I believe most of the
patches from Karmic are upstream now, so it'll be a simple matter of

> news, OTOH, is that over the past month my fixes for these symptoms
> (including the infrastructure) have landed in alsa-driver and
> will be available in crack-of-the-day alsa-driver snapshot builds soon
> and/or via linux-backports-modules-alsa-lucid-generic. Additionally,
> there is ongoing work to power down additional nodes for the HDA
> codecs; please find me on IRC (or leave a note via memoserv) if you
> wish to help roll out these fixes for your particular hardware. Please
> have your /proc/asound/card*/codec* handy/pastebinned.
> Thanks,
> Dan
Thanks for this work!

I'm trying to figure out if we can selectively enable this feature or atleast
make it very easy to enable.

> [0] https://lists.ubuntu.com/archives/ubuntu-devel-discuss/2009-May/008239.html


Amit Kucheria, Kernel Engineer || amit.kucheria at canonical.com

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Amit Kucheria, Kernel Engineer || amit.kucheria at canonical.com

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