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Diffstat (limited to 'Documentation/sound')
| -rw-r--r-- | Documentation/sound/alsa/HD-Audio.txt | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/sound/alsa/HD-Audio.txt b/Documentation/sound/alsa/HD-Audio.txt index c82beb00763..ba2a155f3a3 100644 --- a/Documentation/sound/alsa/HD-Audio.txt +++ b/Documentation/sound/alsa/HD-Audio.txt @@ -524,6 +524,53 @@ power-saving. See /sys/module/snd_hda_intel/parameters/power_save to check the current value. If it's non-zero, the feature is turned on. +Tracepoints +~~~~~~~~~~~ +The hd-audio driver gives a few basic tracepoints. +`hda:hda_send_cmd` traces each CORB write while `hda:hda_get_response` +traces the response from RIRB (only when read from the codec driver). +`hda:hda_bus_reset` traces the bus-reset due to fatal error, etc, and +`hda:hda_power_down` and `hda:hda_power_up` trace the power down/up +via power-saving behavior. + +Enabling all tracepoints can be done like +------------------------------------------------------------------------ + # echo 1 > /sys/kernel/debug/tracing/events/hda/enable +------------------------------------------------------------------------ +then after some commands, you can traces from +/sys/kernel/debug/tracing/trace file. For example, when you want to +trace what codec command is sent, enable the tracepoint like: +------------------------------------------------------------------------ + # cat /sys/kernel/debug/tracing/trace + # tracer: nop + # + # TASK-PID CPU# TIMESTAMP FUNCTION + # | | | | | + <...>-7807 [002] 105147.774889: hda_send_cmd: [0:0] val=e3a019 + <...>-7807 [002] 105147.774893: hda_send_cmd: [0:0] val=e39019 + <...>-7807 [002] 105147.999542: hda_send_cmd: [0:0] val=e3a01a + <...>-7807 [002] 105147.999543: hda_send_cmd: [0:0] val=e3901a + <...>-26764 [001] 349222.837143: hda_send_cmd: [0:0] val=e3a019 + <...>-26764 [001] 349222.837148: hda_send_cmd: [0:0] val=e39019 + <...>-26764 [001] 349223.058539: hda_send_cmd: [0:0] val=e3a01a + <...>-26764 [001] 349223.058541: hda_send_cmd: [0:0] val=e3901a +------------------------------------------------------------------------ +Here `[0:0]` indicates the card number and the codec address, and +`val` shows the value sent to the codec, respectively. The value is +a packed value, and you can decode it via hda-decode-verb program +included in hda-emu package below. For example, the value e3a019 is +to set the left output-amp value to 25. +------------------------------------------------------------------------ + % hda-decode-verb 0xe3a019 + raw value = 0x00e3a019 + cid = 0, nid = 0x0e, verb = 0x3a0, parm = 0x19 + raw value: verb = 0x3a0, parm = 0x19 + verbname = set_amp_gain_mute + amp raw val = 0xa019 + output, left, idx=0, mute=0, val=25 +------------------------------------------------------------------------ + + Development Tree ~~~~~~~~~~~~~~~~ The latest development codes for HD-audio are found on sound git tree: |