[alsa-devel] bug

[Ricard Wanderlof]

On Mon, 30 Mar 2015, Nikita N. wrote:

> We are the devs involved in dCore porting, and that is one of our users
> report:
> http://forum.tinycorelinux.net/index.php/topic,18225
> 
> We verified that in few of our legacy laptops.
> It didn't reproduce for every laptop, but indeed in a couple of them,
> the temperature of the speakers reached extremes levels in few seconds,
> only unplugging the AC/DC cable saved them.
> This is a serious problem in our opinion, and we would hate to see our
> dCore reputation spoiled.
> We hate to admit, but it is *NOT* our bug, and would hate to see this
> bug reverse engineered into a virus/malware (on Linux, or other OS) and
> see ourselves blamed for it.
> So we would like to keep the incident quiet, and we are going to remove
> that thread from our forum.
> On the other side, we would expect any action from ALSA project in
> removing that tool and/or exposing the real individual/s guilty of
> writing that tool.

First of all, I can't say I'm representing the ALSA project or anyone else 
in this matter, so the following is just my personal opinion. Furthermore 
I have no real experience with the mixer application under discussion 
(alsamixergui), but on the face of it it just looks like any mixer 
application.

>From the thread linked above, it seems that if someone maxes out all 
controls in the mixer, this results in a high-pitched whine in the 
speakers, which on certain laptops seem to cause the destruction of 
something in the machine (likely the speakers themselves). It is further 
speculated in the thread that what might be happening is acoustic feedback 
from the speakers to the microphone, which would make sense given the 
results, but would seem strange from a system design point of view.

First of all, it would seem that this wouldn't be dependent on a 
particular mixer application such as alsamixergui, but should be able to 
happen with any mixer application, given the appropriate settings.

Secondly, if you believe that alsamixergui specifically is missbehaving, 
why don't you just take it out of your distribution (dCore)?

Thirdly, and perhaps most importantly, this seems to be a hardware 
problem. If the drive capability of the laptops's output stage is too much 
for the speakers, then there is a serious design flaw in the hardware. 
Given the proliferation of cheap PC hardware this is not surprising, but 
it is hardly a software problem.

And finally, as Clemens said, alsamixergui is not created by the ALSA 
project, so this mailing list is the wrong place to look if none other 
than for that particular reason.

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30