Headphone volume adjustment

James Cameron quozl at laptop.org
Fri Jul 5 02:40:31 EDT 2013

On Thu, Jul 04, 2013 at 07:05:18PM +1000, James Cameron wrote:
> On Tue, Jun 25, 2013 at 01:57:28AM -0400, John Watlington wrote:
> > We have noticed that under Fedora 18 (13.2.0 os10 on XO-4), the
> > headphone volume can't be adjusted to complete silence.
> I've looked into this, and have a tentative patch.  I'd like it
> reviewed to see if the general direction is good.  It works for me.
> Once the volume falls below a minimum value the audio is muted.
> Now, one would think that the mute bits should work, but they did not;
> still had audio in headphones after being sure the mute bits in the
> headphone volume register were set.

My mistake.  Two parts of my code were writing to the mute bits.  It
was necessary to isolate the manipulation of the register bits to one
place in the code.

Fixed for XO-4 in:


Please test with kernel:


The same fix doesn't seem necessary for XO-1.75 yet, until we fix the
"only three useful volume settings" problem.

James Cameron

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