Bug#658728: patch_realtek: no more sound on HP Compaq dx2200 MT

[Jonathan Nieder <jrnieder@gmail.com>]

A. Costa wrote:
> Jonathan Nieder <jrnieder@gmail.com> wrote:

>> The "Auto-Mute Mode" setting persists across reboots...
>
> Aha, I'd (mistakenly) believed the opposite.  Does an "Auto-Mute Mode" 
> setting also persist between kernel upgrades?

Yes, as long as both kernels offer the control.

>> ...See /etc/init.d/alsa-utils for details.
>
> OK, so where does that init script store its persistent 'mute' mode
> state?  That's what should be compared between kernels and bootups I'd
> suppose.

Sure, but that mechanism works, so it has nothing to do with this bug.
;-)

Here are two ways to check whether the patch_realtek bug is fixed.
Either one is sufficient.

 A. Check if the "auto-mute mode" control is offered by alsamixer -c0.
    In a working kernel, if it is offered, then it should have the
    following effect:

     - if auto-mute mode is disabled, sound is output to speakers
       regardless of whether headphones are plugged in

     - if auto-mute mode is enabled, sound is output to speakers if
       and only if headphones are not plugged in

    If it is not offered, then sound should be output to speakers
    if and only if headphones are not plugged in, just as though
    the auto-mute mode control were offered and set to "on".

 B. Check if rebooting from a broken kernel to the current one cures
    the silent output.  That is:

    1. Boot a broken kernel and enable the "auto-mute mode" control,
       so output is inappropriately suppressed.

    2. Boot into the kernel to be tested.  If output is still silent
       regardless of the "alsamixer -c0" volume control setting, it
       is broken.  If output is present, it is fixed.

Thanks for your help,
Jonathan