[Bug 842] New: Whenever possible, Amp Mode should be Off

bugzilla-daemon at bugzilla.openmoko.org bugzilla-daemon at bugzilla.openmoko.org
Thu Sep 13 14:48:42 CEST 2007


           Summary: Whenever possible, Amp Mode should be Off
           Product: OpenMoko
           Version: current svn head
          Platform: Neo1973
        OS/Version: Linux
            Status: NEW
          Severity: major
          Priority: P2
         Component: kernel
        AssignedTo: graeme.gregory at wolfsonmicro.com
        ReportedBy: Tuukka.Hastrup at iki.fi
                CC: buglog at lists.openmoko.org

When Amp Mode isn't Off, the amp draws a lot of current. Whenever no sound is
produced, the kernel sound driver should keep the chip in that mode:

1. Whenever the system is powered off
2. Whenever the sound driver is not loaded
3. Whenever the system is in the suspend mode
4. Whenever the the sound device isn't open by any process

However, there are at least the following exceptions:
1. We are on a GSM call
2. We are functioning as a bluetooth headset

Based on a discussion with SpeedEvil and XorA on IRC, it would seem it would be
preferable to handle these exceptions by being able to defer the policy to
userspace in cases 3 and 4. The mechanism could be a sysfs entry or a new mixer
setting "Amp Auto Poweroff" with values true and false. This setting should only
affect cases 3 and 4.

XorA said on IRC: "Amp Mode to off should be added in suspend function in
neo1973_wm8753.c" and "Im due to do some work on sound suspend soon". Also
assinging the bug to him per his request.

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