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Commit | Line | Data |
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1da177e4 LT |
1 | An OSS/Lite Driver for the ESS Maestro3 family of sound chips |
2 | ||
3 | Zach Brown, January 2001 | |
4 | ||
5 | Driver Status and Availability | |
6 | ------------------------------ | |
7 | ||
8 | The most recent version of this driver will hopefully always be available at | |
9 | http://www.zabbo.net/maestro3/ | |
10 | ||
11 | I will try and maintain the most recent stable version of the driver | |
12 | in both the stable and development kernel lines. | |
13 | ||
14 | Historically I've sucked pretty hard at actually doing that, however. | |
15 | ||
16 | ESS Maestro3 Chip Family | |
17 | ----------------------- | |
18 | ||
19 | The 'Maestro3' is much like the Maestro2 chip. The noted improvement | |
20 | is the removal of the silicon in the '2' that did PCM mixing. All that | |
21 | work is now done through a custom DSP called the ASSP, the Asynchronus | |
22 | Specific Signal Processor. | |
23 | ||
24 | The 'Allegro' is a baby version of the Maestro3. I'm not entirely clear | |
25 | on the extent of the differences, but the driver supports them both :) | |
26 | ||
27 | The 'Allegro' shows up as PCI ID 0x1988 and the Maestro3 as 0x1998, | |
28 | both under ESS's vendor ID of 0x125D. The Maestro3 can also show up as | |
29 | 0x199a when hardware strapping is used. | |
30 | ||
31 | The chip can also act as a multi function device. The modem IDs follow | |
32 | the audio multimedia device IDs. (so the modem part of an Allegro shows | |
33 | up as 0x1989) | |
34 | ||
35 | Driver OSS Behavior | |
36 | -------------------- | |
37 | ||
38 | This OSS driver exports /dev/mixer and /dev/dsp to applications, which | |
39 | mostly adhere to the OSS spec. This driver doesn't register itself | |
40 | with /dev/sndstat, so don't expect information to appear there. | |
41 | ||
42 | The /dev/dsp device exported behaves as expected. Playback is | |
43 | supported in all the various lovely formats. 8/16bit stereo/mono from | |
44 | 8khz to 48khz, with both read()/write(), and mmap(). | |
45 | ||
46 | /dev/mixer is an interface to the AC'97 codec on the Maestro3. It is | |
47 | worth noting that there are a variety of AC'97s that can be wired to | |
48 | the Maestro3. Which is used is entirely up to the hardware implementor. | |
49 | This should only be visible to the user by the presence, or lack, of | |
50 | 'Bass' and 'Treble' sliders in the mixer. Not all AC'97s have them. | |
51 | The Allegro has an onchip AC'97. | |
52 | ||
53 | The driver doesn't support MIDI or FM playback at the moment. | |
54 | ||
55 | Compiling and Installing | |
56 | ------------------------ | |
57 | ||
58 | With the drivers inclusion into the kernel, compiling and installing | |
59 | is the same as most OSS/Lite modular sound drivers. Compilation | |
60 | of the driver is enabled through the CONFIG_SOUND_MAESTRO3 variable | |
61 | in the config system. | |
62 | ||
63 | It may be modular or statically linked. If it is modular it should be | |
64 | installed with the rest of the modules for the kernel on the system. | |
65 | Typically this will be in /lib/modules/ somewhere. 'alias sound-slot-0 | |
66 | maestro3' should also be added to your module configs (typically | |
67 | /etc/modprobe.conf) if you're using modular OSS/Lite sound and want to | |
68 | default to using a maestro3 chip. | |
69 | ||
70 | There are very few options to the driver. One is 'debug' which will | |
71 | tell the driver to print minimal debugging information as it runs. This | |
72 | can be collected with 'dmesg' or through the klogd daemon. | |
73 | ||
74 | One is 'external_amp', which tells the driver to attempt to enable | |
75 | an external amplifier. This defaults to '1', you can tell the driver | |
76 | not to bother enabling such an amplifier by setting it to '0'. | |
77 | ||
78 | And the last is 'gpio_pin', which tells the driver which GPIO pin number | |
79 | the external amp uses (0-15), The Allegro uses 8 by default, all others 1. | |
80 | If everything loads correctly and seems to be working but you get no sound, | |
81 | try tweaking this value. | |
82 | ||
83 | Systems known to need a different value | |
84 | Panasonic ToughBook CF-72: gpio_pin=13 | |
85 | ||
86 | Power Management | |
87 | ---------------- | |
88 | ||
89 | This driver has a minimal understanding of PCI Power Management. It will | |
90 | try and power down the chip when the system is suspended, and power | |
91 | it up with it is resumed. It will also try and power down the chip | |
92 | when the machine is shut down. |