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    SubjectRe: Audio crackles with 4.1-rc1
    At Thu, 30 Apr 2015 16:01:31 +0100,
    Jonathan McDowell wrote:
    >
    > On Wed, Apr 29, 2015 at 01:54:57PM +0200, Takashi Iwai wrote:
    > > At Wed, 29 Apr 2015 12:28:59 +0100,
    > > Jonathan McDowell wrote:
    > > >
    > > > On Tue, Apr 28, 2015 at 04:43:00PM +0200, Takashi Iwai wrote:
    > > > > At Tue, 28 Apr 2015 15:05:20 +0200,
    > > > > Takashi Iwai wrote:
    > > > > > At Tue, 28 Apr 2015 13:35:18 +0100,
    > > > > > Jonathan McDowell wrote:
    > > > > > > On Tue, Apr 28, 2015 at 02:00:17PM +0200, Takashi Iwai wrote:
    > > > > > > > At Tue, 28 Apr 2015 12:21:57 +0100,
    > > > > > > > Jonathan McDowell wrote:
    > > > > > > >
    > > > > > > > > Having upgraded to 4.1-rc1 from 4.0 I'm now hearing audio
    > > > > > > > > crackles at regular intervals. I'm fairly sure this is due to
    > > > > > > > > the HDA power save as once audio is playing things are fine,
    > > > > > > > > it's just when starting to play audio that I hear the crackle.
    > > > > > > > >
    > > > > > > > > System is a Dell Latitude E7240. I haven't tried a bisect yet
    > > > > > > > > but will attempt to find some time to do so in the next few
    > > > > > > > > days. It looks like there have been some changes in sound/hda/
    > > > > > > > > between 4.0 + 4.1-rc1 so I'll concentrate on those first.
    > > > > > > > >
    > > > > > > > There are lots of code changes and enhancements wrt power saving
    > > > > > > > in 4.1, and bisection won't help so much, I'm afraid.
    > > > > > > >
    > > > > > > > First off, check the device status while you hear crackles. Is
    > > > > > > > the codec in runtime suspend (aka power save)? This can be seen
    > > > > > > > in /sys/bus/hdaudio/devices/*/power/runtime_status. Then check
    > > > > > > > the runtime status of the controller, too, found in
    > > > > > > > /sys/class/sound/card?/device/power/runtime_status.
    > > > > > >
    > > > > > > The cracking is definitely happening with the transition from suspended
    > > > > > > to active:
    > > > > > >
    > > > > > > /sys/class/sound/card0/device/power/runtime_status:suspended
    > > > > > > /sys/class/sound/card1/device/power/runtime_status:active
    > > > > > > /sys/bus/hdaudio/devices/hdaudioC0D0/power/runtime_status:suspended
    > > > > > > /sys/bus/hdaudio/devices/hdaudioC1D0/power/runtime_status:active
    > > > > > >
    > > > > > > card1 + C1D0 were suspended, I hit delete in a terminal to force a
    > > > > > > terminal bell, got the crackle and the state changed to active as above.
    > > > > >
    > > > > > Ah, so it's a click noise that happens only once per runtime PM
    > > > > > transition? I thought it were constant crackling noises from your
    > > > > > description ("regular intervals").
    > > > > >
    > > > > > In anyway, please give alsa-info.sh output on both 4.0 and 4.1.
    > > > >
    > > > > Also, does the click noise occur only at powering up, and not at
    > > > > powering down?
    > > >
    > > > The click is only on the transition from suspended to active; not
    > > > constantly during playback and not when transitioning from active to
    > > > suspended. It doesn't appear 4.0 is doing the suspending at all; there
    > > > are no /sys/bus/hdaudio/devices/*/power/runtime_status files and the
    > > > card runtime_status is always active. alsa-info for 4.0 + 4.1-rc1
    > > > attached.
    > >
    > > OK, thanks for clarification.
    > >
    > > One patch you can try (with or without power_save_node disablement) is
    > > below, it squashes the verb sequences at (runtime) PM resume as we did
    > > for 4.0. Let me know if this changes the behavior.
    >
    > Patch alone has no effect. Patch with power_save_node disablement solves
    > the problem. Didn't try power_save_node disablement without the patch.

    Then please confirm that only power_save_node disablement suffices.
    This can be considered as the least change that can be put to 4.1-rc
    if no better fix is found.


    thanks,

    Takashi


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