[Nexus 7 Original Development] jfmcbrayer:
An update on my sound issues. Whenever the problem happens (generally after 12+ hours of uptime, with any non-stock kernel, including but not limited to Franco's), I get audio stuttering, combined with slow transitions (especially swiping effects) and "bounce back" when swiping between home screens. I finally got around to capturing some debug output from dmesg and logcat.

From dmesg, I get the following looping bits:

7975] usb 1-1: new high speed USB device number 81 using tegra-ehci

<3>[45287.747966] usb 1-1: device descriptor read/64, error -71

<3>[45287.968237] usb 1-1: device descriptor read/64, error -71

<6>[45288.167966] usb 1-1: new high speed USB device number 82 using tegra-ehci

<3>[45288.267963] usb 1-1: device descriptor read/64, error -71

<3>[45288.487965] usb 1-1: device descriptor read/64, error -71

<3>[45288.598318] hub 1-0:1.0: unable to enumerate USB device on port 1

<6>[45288.857984] usb 1-1: new high speed USB device number 83 using tegra-ehci

<3>[45289.278063] usb 1-1: device not accepting address 83, error -71

<6>[45289.367969] usb 1-1: new high speed USB device number 84 using tegra-ehci

<3>[45289.788154] usb 1-1: device not accepting address 84, error -71

<6>[45289.877968] usb 1-1: new high speed USB device number 85 using tegra-ehci

<3>[45289.977962] usb 1-1: device descriptor read/64, error -71

<3>[45290.198234] usb 1-1: device descriptor read/64, error -71

<6>[45290.397968] usb 1-1: new high speed USB device number 86 using tegra-ehci

<3>[45290.498005] usb 1-1: device descriptor read/64, error -71

<3>[45290.717967] usb 1-1: device descriptor read/64, error -71

<3>[45290.828411] hub 1-0:1.0: unable to enumerate USB device on port 1

<6>[45291.077969] usb 1-1: new high speed USB device number 87 using tegra-ehci

<3>[45291.498234] usb 1-1: device not accepting address 87, error -71

<6>[45291.587971] usb 1-1: new high speed USB device number 88 using tegra-ehci

<3>[45292.008176] usb 1-1: device not accepting address 88, error -71

<6>[45292.097968] usb 1-1: new high speed USB device number 89 using tegra-ehci

<3>[45292.197964] usb 1-1: device descriptor read/64, error -71

<3>[45292.417968] usb 1-1: device descriptor read/64, error -71

<6>[45292.617972] usb 1-1: new high speed USB device number 90 using tegra-ehci

<3>[45292.717965] usb 1-1: device descriptor read/64, error -71

<3>[45292.937965] usb 1-1: device descriptor read/64, error -71

<3>[45293.048286] hub 1-0:1.0: unable to enumerate USB device on port 1

<6>[45293.297967] usb 1-1: new high speed USB device number 91 using tegra-ehci

<3>[45293.717971] usb 1-1: device not accepting address 91, error -71

<6>[45293.807972] usb 1-1: new high speed USB device number 92 using tegra-ehci

<3>[45294.228148] usb 1-1: device not accepting address 92, error -71

<6>[45294.317969] usb 1-1: new high speed USB device number 93 using tegra-ehci

<3>[45294.417964] usb 1-1: device descriptor read/64, error -71

<3>[45294.688024] usb 1-1: device descriptor read/64, error -71

<6>[45294.948077] usb 1-1: new high speed USB device number 94 using tegra-ehci

And so on.

And from logcat, the only possibly relevant bits are:

09-10 21:59:10.173 W/audio_hw_primary(127): out_write() limiting sleep time 34284 to 23219

09-10 21:59:10.213 W/audio_hw_primary(127): out_write() limiting sleep time 33921 to 23219

09-10 21:59:10.773 W/audio_hw_primary(127): out_write() limiting sleep time 34827 to 23219

09-10 21:59:10.773 W/audio_hw_primary(127): out_write() limiting sleep time 46438 to 23219

09-10 21:59:10.773 W/audio_hw_primary(127): out_write() limiting sleep time 34829 to 23219

09-10 21:59:11.003 W/audio_hw_primary(127): out_write() limiting sleep time 34646 to 23219

09-10 21:59:11.033 W/audio_hw_primary(127): out_write() limiting sleep time 46076 to 23219

09-10 21:59:11.033 W/audio_hw_primary(127): out_write() limiting sleep time 34467 to 23219

09-10 21:59:11.193 W/audio_hw_primary(127): out_write() limiting sleep time 34827 to 23219

09-10 21:59:12.383 W/audio_hw_primary(127): out_write() limiting sleep time 34827 to 23219

09-10 21:59:12.383 W/audio_hw_primary(127): out_write() limiting sleep time 46438 to 23219

09-10 21:59:12.383 W/audio_hw_primary(127): out_write() limiting sleep time 34829 to 23219

09-10 21:59:12.613 D/dalvikvm(7173): GC_CONCURRENT freed 751K, 9% free 9999K/10952K, paused 3ms+3ms, total 33ms

And so on.

The latter I've seen a reference to here, which is an Android-x86 list, but the patch doesn't seem to be x86-specific. As to the USB looping, I have no idea whatsoever what could be causing it, as I'm not plugging or removing any USB devices at the time. Maybe has to do with USB autosuspend?

I'm guessing the sound stuttering is just a symptom of high load caused by the USB reloading.

Anyway, I know I shouldn't be getting any of these errors, as r75 is so close to stock and shouldn't touch anything affecting either of these. The only thing I can think of is to maybe set up a build environment and build the "stock" sources everyone is starting from to see if it's maybe the released sources not being exactly 100% the same as Google's?