1 ========================== 1 ==========================
2 Proc Files of ALSA Drivers 2 Proc Files of ALSA Drivers
3 ========================== 3 ==========================
4 4
5 Takashi Iwai <tiwai@suse.de> 5 Takashi Iwai <tiwai@suse.de>
6 6
7 General 7 General
8 ======= 8 =======
9 9
10 ALSA has its own proc tree, /proc/asound. Man 10 ALSA has its own proc tree, /proc/asound. Many useful information are
11 found in this tree. When you encounter a prob 11 found in this tree. When you encounter a problem and need debugging,
12 check the files listed in the following sectio 12 check the files listed in the following sections.
13 13
14 Each card has its subtree cardX, where X is fr 14 Each card has its subtree cardX, where X is from 0 to 7. The
15 card-specific files are stored in the ``card*` 15 card-specific files are stored in the ``card*`` subdirectories.
16 16
17 17
18 Global Information 18 Global Information
19 ================== 19 ==================
20 20
21 cards 21 cards
22 Shows the list of currently configured 22 Shows the list of currently configured ALSA drivers,
23 index, the id string, short and long d 23 index, the id string, short and long descriptions.
24 24
25 version 25 version
26 Shows the version string and compile d 26 Shows the version string and compile date.
27 27
28 modules 28 modules
29 Lists the module of each card 29 Lists the module of each card
30 30
31 devices 31 devices
32 Lists the ALSA native device mappings. 32 Lists the ALSA native device mappings.
33 33
34 meminfo 34 meminfo
35 Shows the status of allocated pages vi 35 Shows the status of allocated pages via ALSA drivers.
36 Appears only when ``CONFIG_SND_DEBUG=y 36 Appears only when ``CONFIG_SND_DEBUG=y``.
37 37
38 hwdep 38 hwdep
39 Lists the currently available hwdep de 39 Lists the currently available hwdep devices in format of
40 ``<card>-<device>: <name>`` 40 ``<card>-<device>: <name>``
41 41
42 pcm 42 pcm
43 Lists the currently available PCM devi 43 Lists the currently available PCM devices in format of
44 ``<card>-<device>: <id>: <name> : <sub 44 ``<card>-<device>: <id>: <name> : <sub-streams>``
45 45
46 timer 46 timer
47 Lists the currently available timer de 47 Lists the currently available timer devices
48 48
49 49
50 oss/devices 50 oss/devices
51 Lists the OSS device mappings. 51 Lists the OSS device mappings.
52 52
53 oss/sndstat 53 oss/sndstat
54 Provides the output compatible with /d 54 Provides the output compatible with /dev/sndstat.
55 You can symlink this to /dev/sndstat. 55 You can symlink this to /dev/sndstat.
56 56
57 57
58 Card Specific Files 58 Card Specific Files
59 =================== 59 ===================
60 60
61 The card-specific files are found in ``/proc/a 61 The card-specific files are found in ``/proc/asound/card*`` directories.
62 Some drivers (e.g. cmipci) have their own proc 62 Some drivers (e.g. cmipci) have their own proc entries for the
63 register dump, etc (e.g. ``/proc/asound/card*/ 63 register dump, etc (e.g. ``/proc/asound/card*/cmipci`` shows the register
64 dump). These files would be really helpful fo 64 dump). These files would be really helpful for debugging.
65 65
66 When PCM devices are available on this card, y 66 When PCM devices are available on this card, you can see directories
67 like pcm0p or pcm1c. They hold the PCM inform 67 like pcm0p or pcm1c. They hold the PCM information for each PCM
68 stream. The number after ``pcm`` is the PCM d 68 stream. The number after ``pcm`` is the PCM device number from 0, and
69 the last ``p`` or ``c`` means playback or capt 69 the last ``p`` or ``c`` means playback or capture direction. The files in
70 this subtree is described later. 70 this subtree is described later.
71 71
72 The status of MIDI I/O is found in ``midi*`` f 72 The status of MIDI I/O is found in ``midi*`` files. It shows the device
73 name and the received/transmitted bytes throug 73 name and the received/transmitted bytes through the MIDI device.
74 74
75 When the card is equipped with AC97 codecs, th 75 When the card is equipped with AC97 codecs, there are ``codec97#*``
76 subdirectories (described later). 76 subdirectories (described later).
77 77
78 When the OSS mixer emulation is enabled (and t 78 When the OSS mixer emulation is enabled (and the module is loaded),
79 oss_mixer file appears here, too. This shows 79 oss_mixer file appears here, too. This shows the current mapping of
80 OSS mixer elements to the ALSA control element 80 OSS mixer elements to the ALSA control elements. You can change the
81 mapping by writing to this device. Read OSS-E 81 mapping by writing to this device. Read OSS-Emulation.txt for
82 details. 82 details.
83 83
84 84
85 PCM Proc Files 85 PCM Proc Files
86 ============== 86 ==============
87 87
88 ``card*/pcm*/info`` 88 ``card*/pcm*/info``
89 The general information of this PCM de 89 The general information of this PCM device: card #, device #,
90 substreams, etc. 90 substreams, etc.
91 91
92 ``card*/pcm*/xrun_debug`` 92 ``card*/pcm*/xrun_debug``
93 This file appears when ``CONFIG_SND_DE 93 This file appears when ``CONFIG_SND_DEBUG=y`` and
94 ``CONFIG_SND_PCM_XRUN_DEBUG=y``. 94 ``CONFIG_SND_PCM_XRUN_DEBUG=y``.
95 This shows the status of xrun (= buffe 95 This shows the status of xrun (= buffer overrun/xrun) and
96 invalid PCM position debug/check of AL 96 invalid PCM position debug/check of ALSA PCM middle layer.
97 It takes an integer value, can be chan 97 It takes an integer value, can be changed by writing to this
98 file, such as:: 98 file, such as::
99 99
100 # echo 5 > /proc/asound/card0 100 # echo 5 > /proc/asound/card0/pcm0p/xrun_debug
101 101
102 The value consists of the following bi 102 The value consists of the following bit flags:
103 103
104 * bit 0 = Enable XRUN/jiffies debug me 104 * bit 0 = Enable XRUN/jiffies debug messages
105 * bit 1 = Show stack trace at XRUN / j 105 * bit 1 = Show stack trace at XRUN / jiffies check
106 * bit 2 = Enable additional jiffies ch 106 * bit 2 = Enable additional jiffies check
107 107
108 When the bit 0 is set, the driver will 108 When the bit 0 is set, the driver will show the messages to
109 kernel log when an xrun is detected. 109 kernel log when an xrun is detected. The debug message is
110 shown also when the invalid H/W pointe 110 shown also when the invalid H/W pointer is detected at the
111 update of periods (usually called from 111 update of periods (usually called from the interrupt
112 handler). 112 handler).
113 113
114 When the bit 1 is set, the driver will 114 When the bit 1 is set, the driver will show the stack trace
115 additionally. This may help the debug 115 additionally. This may help the debugging.
116 116
117 Since 2.6.30, this option can enable t 117 Since 2.6.30, this option can enable the hwptr check using
118 jiffies. This detects spontaneous inv 118 jiffies. This detects spontaneous invalid pointer callback
119 values, but can be lead to too much co 119 values, but can be lead to too much corrections for a (mostly
120 buggy) hardware that doesn't give smoo 120 buggy) hardware that doesn't give smooth pointer updates.
121 This feature is enabled via the bit 2. 121 This feature is enabled via the bit 2.
122 122
123 ``card*/pcm*/sub*/info`` 123 ``card*/pcm*/sub*/info``
124 The general information of this PCM su 124 The general information of this PCM sub-stream.
125 125
126 ``card*/pcm*/sub*/status`` 126 ``card*/pcm*/sub*/status``
127 The current status of this PCM sub-str 127 The current status of this PCM sub-stream, elapsed time,
128 H/W position, etc. 128 H/W position, etc.
129 129
130 ``card*/pcm*/sub*/hw_params`` 130 ``card*/pcm*/sub*/hw_params``
131 The hardware parameters set for this s 131 The hardware parameters set for this sub-stream.
132 132
133 ``card*/pcm*/sub*/sw_params`` 133 ``card*/pcm*/sub*/sw_params``
134 The soft parameters set for this sub-s 134 The soft parameters set for this sub-stream.
135 135
136 ``card*/pcm*/sub*/prealloc`` 136 ``card*/pcm*/sub*/prealloc``
137 The buffer pre-allocation information. 137 The buffer pre-allocation information.
138 138
139 ``card*/pcm*/sub*/xrun_injection`` 139 ``card*/pcm*/sub*/xrun_injection``
140 Triggers an XRUN to the running stream 140 Triggers an XRUN to the running stream when any value is
141 written to this proc file. Used for f 141 written to this proc file. Used for fault injection.
142 This entry is write-only. 142 This entry is write-only.
143 143
144 AC97 Codec Information 144 AC97 Codec Information
145 ====================== 145 ======================
146 146
147 ``card*/codec97#*/ac97#?-?`` 147 ``card*/codec97#*/ac97#?-?``
148 Shows the general information of this 148 Shows the general information of this AC97 codec chip, such as
149 name, capabilities, set up. 149 name, capabilities, set up.
150 150
151 ``card*/codec97#0/ac97#?-?+regs`` 151 ``card*/codec97#0/ac97#?-?+regs``
152 Shows the AC97 register dump. Useful 152 Shows the AC97 register dump. Useful for debugging.
153 153
154 When CONFIG_SND_DEBUG is enabled, you 154 When CONFIG_SND_DEBUG is enabled, you can write to this file for
155 changing an AC97 register directly. P 155 changing an AC97 register directly. Pass two hex numbers.
156 For example, 156 For example,
157 157
158 :: 158 ::
159 159
160 # echo 02 9f1f > /proc/asound/card0/co 160 # echo 02 9f1f > /proc/asound/card0/codec97#0/ac97#0-0+regs
161 161
162 162
163 USB Audio Streams 163 USB Audio Streams
164 ================= 164 =================
165 165
166 ``card*/stream*`` 166 ``card*/stream*``
167 Shows the assignment and the current s 167 Shows the assignment and the current status of each audio stream
168 of the given card. This information i 168 of the given card. This information is very useful for debugging.
169 169
170 170
171 HD-Audio Codecs 171 HD-Audio Codecs
172 =============== 172 ===============
173 173
174 ``card*/codec#*`` 174 ``card*/codec#*``
175 Shows the general codec information an 175 Shows the general codec information and the attribute of each
176 widget node. 176 widget node.
177 177
178 ``card*/eld#*`` 178 ``card*/eld#*``
179 Available for HDMI or DisplayPort inte 179 Available for HDMI or DisplayPort interfaces.
180 Shows ELD(EDID Like Data) info retriev 180 Shows ELD(EDID Like Data) info retrieved from the attached HDMI sink,
181 and describes its audio capabilities a 181 and describes its audio capabilities and configurations.
182 182
183 Some ELD fields may be modified by doi 183 Some ELD fields may be modified by doing ``echo name hex_value > eld#*``.
184 Only do this if you are sure the HDMI 184 Only do this if you are sure the HDMI sink provided value is wrong.
185 And if that makes your HDMI audio work 185 And if that makes your HDMI audio work, please report to us so that we
186 can fix it in future kernel releases. 186 can fix it in future kernel releases.
187 187
188 188
189 Sequencer Information 189 Sequencer Information
190 ===================== 190 =====================
191 191
192 seq/drivers 192 seq/drivers
193 Lists the currently available ALSA seq 193 Lists the currently available ALSA sequencer drivers.
194 194
195 seq/clients 195 seq/clients
196 Shows the list of currently available 196 Shows the list of currently available sequencer clients and
197 ports. The connection status and the 197 ports. The connection status and the running status are shown
198 in this file, too. 198 in this file, too.
199 199
200 seq/queues 200 seq/queues
201 Lists the currently allocated/running 201 Lists the currently allocated/running sequencer queues.
202 202
203 seq/timer 203 seq/timer
204 Lists the currently allocated/running 204 Lists the currently allocated/running sequencer timers.
205 205
206 seq/oss 206 seq/oss
207 Lists the OSS-compatible sequencer stu 207 Lists the OSS-compatible sequencer stuffs.
208 208
209 209
210 Help For Debugging? 210 Help For Debugging?
211 =================== 211 ===================
212 212
213 When the problem is related with PCM, first tr 213 When the problem is related with PCM, first try to turn on xrun_debug
214 mode. This will give you the kernel messages 214 mode. This will give you the kernel messages when and where xrun
215 happened. 215 happened.
216 216
217 If it's really a bug, report it with the follo 217 If it's really a bug, report it with the following information:
218 218
219 - the name of the driver/card, show in ``/proc 219 - the name of the driver/card, show in ``/proc/asound/cards``
220 - the register dump, if available (e.g. ``card 220 - the register dump, if available (e.g. ``card*/cmipci``)
221 221
222 when it's a PCM problem, 222 when it's a PCM problem,
223 223
224 - set-up of PCM, shown in hw_parms, sw_params, 224 - set-up of PCM, shown in hw_parms, sw_params, and status in the PCM
225 sub-stream directory 225 sub-stream directory
226 226
227 when it's a mixer problem, 227 when it's a mixer problem,
228 228
229 - AC97 proc files, ``codec97#*/*`` files 229 - AC97 proc files, ``codec97#*/*`` files
230 230
231 for USB audio/midi, 231 for USB audio/midi,
232 232
233 - output of ``lsusb -v`` 233 - output of ``lsusb -v``
234 - ``stream*`` files in card directory 234 - ``stream*`` files in card directory
235 235
236 236
237 The ALSA bug-tracking system is found at: 237 The ALSA bug-tracking system is found at:
238 https://bugtrack.alsa-project.org/alsa-bug/ 238 https://bugtrack.alsa-project.org/alsa-bug/
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