Date: Wed, 29 Aug 2018 18:13:01 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-arm@FreeBSD.org Subject: [Bug 231004] powerd causes click noises on RPi pcm audio using 12-CURRENT Message-ID: <bug-231004-7@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D231004 Bug ID: 231004 Summary: powerd causes click noises on RPi pcm audio using 12-CURRENT Product: Base System Version: CURRENT Hardware: arm OS: Any Status: New Severity: Affects Some People Priority: --- Component: arm Assignee: freebsd-arm@FreeBSD.org Reporter: bobf@mrp3.com when running powerd on an RPi model 2B, audible 'click' noises can be heard= on the RPi pcm audio output (both channels simultaneously), loud enough to be disruptive. However, these noises do not appear to happen when the CPU is sufficiently utilized, such as when playing a media file. As such, it may have been happening for a long time but had gone unnoticed. The CPU frequency changes from powerd appear to be the root cause. Loading= the BCM PWM kernel driver has no effect (whether present or absent in the kerne= l). Steps to repro: a) run an application that opens the audio output (/dev/dsp0.0) but doesn't send any signals over it. [alternately you can leave it 'unopened' but noise may be more frequent this way if you have it open] b) configure powerd to properly cycle the CPU frequency in rc.conf, and make sure it has been started with 'service powerd start'. c) repeatedly enter 'sysctl hw.cpufreq' into a console, and observe frequen= cy cycling and 'click noises' on the audio output. d) stop powerd with 'service powerd stop'. e) repeat 'c' except no noise. f) rinse/repeat as needed to confirm my settings for powerd are: powerd_enable=3D"YES" powerd_flags=3D"-n hadp -a hadp -b hadp" uname output: FreeBSD pi2c 12.0-ALPHA2 FreeBSD 12.0-ALPHA2 #16 r338208: Wed Aug 22 15:06:= 45 PDT 2018=20=20=20=20 bobf@hack.SFT.local:/e-drive/obj.current/e-drive/src.current/arm.armv7/sys/= RPI2 arm running processes: PID TT STAT TIME COMMAND 0 - DLs 0:00.02 [kernel] 1 - SLs 0:00.08 /sbin/init -- 2 - DL 0:00.00 [crypto] 3 - DL 0:00.00 [crypto returns 0] 4 - DL 0:00.00 [crypto returns 1] 5 - DL 0:00.00 [crypto returns 2] 6 - DL 0:00.00 [crypto returns 3] 7 - DL 0:00.00 [cam] 8 - SL 0:13.08 [VCHIQ-0] 9 - SL 0:01.25 [VCHIQr-0] 10 - RNL 79:00.98 [idle] 11 - WL 0:17.34 [intr] 12 - DL 0:00.30 [geom] 13 - DL 0:04.82 [usb] 14 - IL 0:00.00 [VCHIQs-0] 15 - DL 0:00.00 [sctp_iterator] 16 - DL 0:00.70 [rand_harvestq] 17 - DL 0:00.00 [soaiod1] 18 - DL 0:00.00 [soaiod2] 19 - DL 0:00.00 [soaiod3] 20 - DL 0:00.00 [soaiod4] 21 - DL 0:00.16 [mmcsd0: mmc/sd card] 22 - IL 0:00.00 [VCHIQka-0] 23 - SL 0:03.78 [bcm2835_audio_worke] 24 - DL 0:00.75 [pagedaemon] 25 - DL 0:00.00 [vmdaemon] 26 - DL 0:00.45 [bufdaemon] 27 - DL 0:00.04 [vnlru] 28 - DL 0:00.25 [syncer] 442 - Is 0:00.02 dhclient: system.syslog (dhclient) 445 - Is 0:00.02 dhclient: ue0 [priv] (dhclient) 491 - Is 0:00.00 dhclient: ue0 (dhclient) 492 - Is 0:00.01 /sbin/devd 562 - Ss 0:00.07 /usr/sbin/syslogd -s 773 - Is 0:00.02 /usr/sbin/sshd 777 - Ss 0:00.07 /usr/sbin/cron -s 836 - Is 0:00.18 sshd: ME [priv] (sshd) 839 - I 0:00.07 sshd: ME@pts/0 (sshd) 971 - Ss 0:00.00 /usr/sbin/powerd -n hadp -a hadp -b hadp 835 u0 Is 0:00.19 login [pam] (login) 852 u0 S 0:00.71 -csh (csh) 974 u0 R+ 0:00.02 ps ax 827 v0 Is+ 0:00.03 /usr/libexec/getty Pc ttyv0 828 v1 Is+ 0:00.02 /usr/libexec/getty Pc ttyv1 829 v2 Is+ 0:00.03 /usr/libexec/getty Pc ttyv2 830 v3 Is+ 0:00.02 /usr/libexec/getty Pc ttyv3 831 v4 Is+ 0:00.03 /usr/libexec/getty Pc ttyv4 832 v5 Is+ 0:00.02 /usr/libexec/getty Pc ttyv5 833 v6 Is+ 0:00.04 /usr/libexec/getty Pc ttyv6 834 v7 Is+ 0:00.02 /usr/libexec/getty Pc ttyv7 840 0 Is 0:00.22 -csh (csh) 849 0 S+ 5:47.71 ./ethermidi -F /home/bobf/mysounds.sf2 0.0.0.0:5000 NOTE: the 'ethermidi' application is one that I'm working on; it opens the audio output and idles waiting for MIDI commands over ethernet, and invokes libfluidsynth to play the MIDI sounds via 'oss'. It's not the noise source since this doesn't happen on other platforms with the same application.=20 However, it does reveal that there IS a noise source. --=20 You are receiving this mail because: You are the assignee for the bug.=
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