Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | Proc Files of ALSA Drivers |
| 2 | ========================== |
| 3 | Takashi Iwai <tiwai@suse.de> |
| 4 | |
| 5 | General |
| 6 | ------- |
| 7 | |
| 8 | ALSA has its own proc tree, /proc/asound. Many useful information are |
| 9 | found in this tree. When you encounter a problem and need debugging, |
| 10 | check the files listed in the following sections. |
| 11 | |
| 12 | Each card has its subtree cardX, where X is from 0 to 7. The |
| 13 | card-specific files are stored in the card* subdirectories. |
| 14 | |
| 15 | |
| 16 | Global Information |
| 17 | ------------------ |
| 18 | |
| 19 | cards |
| 20 | Shows the list of currently configured ALSA drivers, |
| 21 | index, the id string, short and long descriptions. |
| 22 | |
| 23 | version |
| 24 | Shows the version string and compile date. |
| 25 | |
| 26 | modules |
| 27 | Lists the module of each card |
| 28 | |
| 29 | devices |
| 30 | Lists the ALSA native device mappings. |
| 31 | |
| 32 | meminfo |
| 33 | Shows the status of allocated pages via ALSA drivers. |
| 34 | Appears only when CONFIG_SND_DEBUG=y. |
| 35 | |
| 36 | hwdep |
| 37 | Lists the currently available hwdep devices in format of |
| 38 | <card>-<device>: <name> |
| 39 | |
| 40 | pcm |
| 41 | Lists the currently available PCM devices in format of |
| 42 | <card>-<device>: <id>: <name> : <sub-streams> |
| 43 | |
| 44 | timer |
| 45 | Lists the currently available timer devices |
| 46 | |
| 47 | |
| 48 | oss/devices |
| 49 | Lists the OSS device mappings. |
| 50 | |
| 51 | oss/sndstat |
| 52 | Provides the output compatible with /dev/sndstat. |
| 53 | You can symlink this to /dev/sndstat. |
| 54 | |
| 55 | |
| 56 | Card Specific Files |
| 57 | ------------------- |
| 58 | |
| 59 | The card-specific files are found in /proc/asound/card* directories. |
| 60 | Some drivers (e.g. cmipci) have their own proc entries for the |
| 61 | register dump, etc (e.g. /proc/asound/card*/cmipci shows the register |
| 62 | dump). These files would be really helpful for debugging. |
| 63 | |
| 64 | When PCM devices are available on this card, you can see directories |
| 65 | like pcm0p or pcm1c. They hold the PCM information for each PCM |
| 66 | stream. The number after 'pcm' is the PCM device number from 0, and |
| 67 | the last 'p' or 'c' means playback or capture direction. The files in |
| 68 | this subtree is described later. |
| 69 | |
| 70 | The status of MIDI I/O is found in midi* files. It shows the device |
| 71 | name and the received/transmitted bytes through the MIDI device. |
| 72 | |
| 73 | When the card is equipped with AC97 codecs, there are codec97#* |
Matt LaPlante | fff9289 | 2006-10-03 22:47:42 +0200 | [diff] [blame] | 74 | subdirectories (described later). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
| 76 | When the OSS mixer emulation is enabled (and the module is loaded), |
| 77 | oss_mixer file appears here, too. This shows the current mapping of |
| 78 | OSS mixer elements to the ALSA control elements. You can change the |
| 79 | mapping by writing to this device. Read OSS-Emulation.txt for |
| 80 | details. |
| 81 | |
| 82 | |
| 83 | PCM Proc Files |
| 84 | -------------- |
| 85 | |
| 86 | card*/pcm*/info |
| 87 | The general information of this PCM device: card #, device #, |
| 88 | substreams, etc. |
| 89 | |
| 90 | card*/pcm*/xrun_debug |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 91 | This file appears when CONFIG_SND_DEBUG=y and |
| 92 | CONFIG_PCM_XRUN_DEBUG=y. |
| 93 | This shows the status of xrun (= buffer overrun/xrun) and |
| 94 | invalid PCM position debug/check of ALSA PCM middle layer. |
| 95 | It takes an integer value, can be changed by writing to this |
| 96 | file, such as |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 97 | |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 98 | # cat 5 > /proc/asound/card0/pcm0p/xrun_debug |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 100 | The value consists of the following bit flags: |
| 101 | bit 0 = Enable XRUN/jiffies debug messages |
| 102 | bit 1 = Show stack trace at XRUN / jiffies check |
| 103 | bit 2 = Enable additional jiffies check |
Takashi Iwai | cedb811 | 2009-07-23 11:04:13 +0200 | [diff] [blame] | 104 | bit 3 = Log hwptr update at each period interrupt |
| 105 | bit 4 = Log hwptr update at each snd_pcm_update_hw_ptr() |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 106 | |
| 107 | When the bit 0 is set, the driver will show the messages to |
| 108 | kernel log when an xrun is detected. The debug message is |
| 109 | shown also when the invalid H/W pointer is detected at the |
| 110 | update of periods (usually called from the interrupt |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 111 | handler). |
| 112 | |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 113 | When the bit 1 is set, the driver will show the stack trace |
| 114 | additionally. This may help the debugging. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 116 | Since 2.6.30, this option can enable the hwptr check using |
Takashi Iwai | c87d973 | 2009-05-27 10:53:33 +0200 | [diff] [blame] | 117 | jiffies. This detects spontaneous invalid pointer callback |
| 118 | values, but can be lead to too much corrections for a (mostly |
| 119 | buggy) hardware that doesn't give smooth pointer updates. |
Takashi Iwai | 4f64e15 | 2009-06-11 16:14:11 +0200 | [diff] [blame] | 120 | This feature is enabled via the bit 2. |
Takashi Iwai | c87d973 | 2009-05-27 10:53:33 +0200 | [diff] [blame] | 121 | |
Takashi Iwai | cedb811 | 2009-07-23 11:04:13 +0200 | [diff] [blame] | 122 | Bits 3 and 4 are for logging the hwptr records. Note that |
| 123 | these will give flood of kernel messages. |
| 124 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | card*/pcm*/sub*/info |
| 126 | The general information of this PCM sub-stream. |
| 127 | |
| 128 | card*/pcm*/sub*/status |
| 129 | The current status of this PCM sub-stream, elapsed time, |
| 130 | H/W position, etc. |
| 131 | |
| 132 | card*/pcm*/sub*/hw_params |
| 133 | The hardware parameters set for this sub-stream. |
| 134 | |
| 135 | card*/pcm*/sub*/sw_params |
| 136 | The soft parameters set for this sub-stream. |
| 137 | |
| 138 | card*/pcm*/sub*/prealloc |
| 139 | The buffer pre-allocation information. |
| 140 | |
| 141 | |
| 142 | AC97 Codec Information |
| 143 | ---------------------- |
| 144 | |
| 145 | card*/codec97#*/ac97#?-? |
| 146 | Shows the general information of this AC97 codec chip, such as |
| 147 | name, capabilities, set up. |
| 148 | |
| 149 | card*/codec97#0/ac97#?-?+regs |
| 150 | Shows the AC97 register dump. Useful for debugging. |
| 151 | |
| 152 | When CONFIG_SND_DEBUG is enabled, you can write to this file for |
| 153 | changing an AC97 register directly. Pass two hex numbers. |
| 154 | For example, |
| 155 | |
| 156 | # echo 02 9f1f > /proc/asound/card0/codec97#0/ac97#0-0+regs |
| 157 | |
| 158 | |
Takashi Iwai | 59de641 | 2005-11-17 11:05:34 +0100 | [diff] [blame] | 159 | USB Audio Streams |
| 160 | ----------------- |
| 161 | |
| 162 | card*/stream* |
| 163 | Shows the assignment and the current status of each audio stream |
| 164 | of the given card. This information is very useful for debugging. |
| 165 | |
| 166 | |
| 167 | HD-Audio Codecs |
| 168 | --------------- |
| 169 | |
| 170 | card*/codec#* |
| 171 | Shows the general codec information and the attribute of each |
| 172 | widget node. |
| 173 | |
Wu Fengguang | a5fcf89 | 2008-11-22 09:40:55 +0800 | [diff] [blame] | 174 | card*/eld#* |
| 175 | Available for HDMI or DisplayPort interfaces. |
| 176 | Shows ELD(EDID Like Data) info retrieved from the attached HDMI sink, |
| 177 | and describes its audio capabilities and configurations. |
| 178 | |
| 179 | Some ELD fields may be modified by doing `echo name hex_value > eld#*`. |
| 180 | Only do this if you are sure the HDMI sink provided value is wrong. |
| 181 | And if that makes your HDMI audio work, please report to us so that we |
| 182 | can fix it in future kernel releases. |
| 183 | |
Takashi Iwai | 59de641 | 2005-11-17 11:05:34 +0100 | [diff] [blame] | 184 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 185 | Sequencer Information |
| 186 | --------------------- |
| 187 | |
| 188 | seq/drivers |
| 189 | Lists the currently available ALSA sequencer drivers. |
| 190 | |
| 191 | seq/clients |
Matt LaPlante | 53cb472 | 2006-10-03 22:55:17 +0200 | [diff] [blame] | 192 | Shows the list of currently available sequencer clients and |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | ports. The connection status and the running status are shown |
| 194 | in this file, too. |
| 195 | |
| 196 | seq/queues |
Matt LaPlante | 53cb472 | 2006-10-03 22:55:17 +0200 | [diff] [blame] | 197 | Lists the currently allocated/running sequencer queues. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | |
| 199 | seq/timer |
| 200 | Lists the currently allocated/running sequencer timers. |
| 201 | |
| 202 | seq/oss |
| 203 | Lists the OSS-compatible sequencer stuffs. |
| 204 | |
| 205 | |
| 206 | Help For Debugging? |
| 207 | ------------------- |
| 208 | |
| 209 | When the problem is related with PCM, first try to turn on xrun_debug |
| 210 | mode. This will give you the kernel messages when and where xrun |
| 211 | happened. |
| 212 | |
Matt LaPlante | d6bc8ac | 2006-10-03 22:54:15 +0200 | [diff] [blame] | 213 | If it's really a bug, report it with the following information: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | |
| 215 | - the name of the driver/card, show in /proc/asound/cards |
Matt LaPlante | d6bc8ac | 2006-10-03 22:54:15 +0200 | [diff] [blame] | 216 | - the register dump, if available (e.g. card*/cmipci) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 217 | |
| 218 | when it's a PCM problem, |
| 219 | |
| 220 | - set-up of PCM, shown in hw_parms, sw_params, and status in the PCM |
| 221 | sub-stream directory |
| 222 | |
| 223 | when it's a mixer problem, |
| 224 | |
| 225 | - AC97 proc files, codec97#*/* files |
| 226 | |
| 227 | for USB audio/midi, |
| 228 | |
| 229 | - output of lsusb -v |
| 230 | - stream* files in card directory |
| 231 | |
| 232 | |
| 233 | The ALSA bug-tracking system is found at: |
| 234 | |
| 235 | https://bugtrack.alsa-project.org/alsa-bug/ |