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- Lines: 230
Tue Oct 19 17:14:00 1999
- Orig file:
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.2.12/linux/Documentation/sound/NM256 linux/Documentation/sound/NM256
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+Documentation for the NeoMagic 256AV/256ZX sound driver
+You're looking at version 1.0 of the driver. (Woohoo!) It has been
+successfully tested against the following laptop models:
+ Sony Z505S/Z505SX/Z505DX
+ Sony F150, F160, F180, F250, F270, F280, PCG-F26
+ Dell Latitude CPi, CPt (various submodels)
+There are a few caveats, which is why you should read the entirety of
+this document first.
+This driver was developed without any support or assistance from
+NeoMagic. There is no warranty, expressed, implied, or otherwise. It
+is free software in the public domain; feel free to use it, sell it,
+give it to your best friends, even claim that you wrote it (but why?!)
+but don't come whining to me, NeoMagic, Sony, Dell, or anyone else
+when it blows up your computer.
+Enable the sound drivers, the OSS sound drivers, and then the NM256
+driver. The NM256 driver *must* be configured as a module (it won't
+give you any other choice).
+Next, do the usual "make modules" and "make modules_install".
+Finally, insmod the soundcore, sound and nm256 modules.
+When the nm256 driver module is loaded, you should see a couple of
+confirmation messages in the kernel logfile indicating that it found
+the device (the device does *not* use any I/O ports or DMA channels).
+Now try playing a wav file, futz with the CD-ROM if you have one, etc.
+The NM256 is entirely a PCI-based device, and all the necessary
+information is automatically obtained from the card. It can only be
+configured as a module in a vain attempt to prevent people from
+hurting themselves. It works correctly if it shares an IRQ with
+another device (it normally shares IRQ 9 with the builtin eepro100
+ethernet on the Sony Z505 laptops).
+It does not run the card in any sort of compatibility mode. Thus it
+almost certainly will not work on laptops that have the
+SB16-compatible codec/mixer; you will want to use the standard SB16
+OSS driver with these chipsets. I cannot provide any assistance with
+machines using the SB-16 compatible version.
+The sound support is very basic, but it does include simultaneous
+playback and record capability. The mixer support is also quite
+simple, although this is in keeping with the rather limited
+functionality of the chipset.
+There is no hardware synthesizer available, as the Losedows OPL-3 and
+MIDI support is done via hardware emulation.
+Only three recording devices are available on the Sony: the
+microphone, the CD-ROM input, and the volume device (which corresponds
+to the stereo output). (Other devices may be available on other
+models of laptops.) The Z505 series does not have a builtin CD-ROM,
+so of course the CD-ROM input doesn't work. It does work on laptops
+with a builtin CD-ROM drive.
+Recording is mono 8-bit only.
+The mixer device does not appear to have any tone controls, at least
+on the Z505 series. The mixer module checks for tone controls in the
+AC97 mixer, and will enable them if they are available.
+ * There are known problems with PCMCIA cards and the eepro100 ethernet
+ driver on the Z505S/Z505SX/Z505DX. Keep reading.
+ * There are also potential problems with using a virtual X display, and
+ also problems loading the module after the X server has been started.
+ Keep reading.
+ * The volume control isn't anywhere near linear. Sorry. This will be
+ fixed eventually, when I get sufficiently annoyed with it. (I doubt
+ it will ever be fixed now, since I've never gotten sufficiently
+ annoyed with it and nobody else seems to care.)
+ * There are reports that the CD-ROM volume is very low. Since I do not
+ have a CD-ROM equipped laptop, I cannot test this (it's kinda hard to
+ do remotely).
+ * Only 8 fixed-rate speeds are supported. This is mainly a chipset
+ limitation. It may be possible to support other speeds in the future.
+ * There is no support for the telephone mixer/codec. There is support
+ for a phonein/phoneout device if your mixer program supports it;
+ whether or not it does anything is anyone's guess. (Reports on this
+ would be appreciated.)
+ * This driver was not written with any cooperation or support from
+ NeoMagic. If you have any questions about this, see their website
+ for their official stance on supporting open source drivers.
+The NeoMagic sound engine uses a portion of the display memory to hold
+the sound buffer. (Crazy, eh?) The NeoMagic video BIOS sets up a
+special pointer at the top of video RAM to indicate where the top of
+the audio buffer should be placed.
+At the present time XFree86 is apparently not aware of this. It will
+thus write over either the pointer or the sound buffer with abandon.
+(Accelerated-X seems to do a better job here.)
+This implies a few things:
+ * Sometimes the NM256 driver has to guess at where the buffer
+ should be placed, especially if the module is loaded after the
+ X server is started. It's usually correct, but it will fail on
+ the Sony F250.
+ * Virtual screens greater than 1024x768x16 under XFree86 are
+ problematic on laptops with only 2.5MB of screen RAM. This
+ includes all of the 256AV-equipped laptops. (Virtual displays
+ may or may not work on the 256ZX, which has at least 4MB of
+ video RAM.)
+If you start having problems with random noise being output either
+constantly (this is the usual symptom on the F250), or when windows
+are moved around (this is the usual symptom when using a virtual
+screen), the best fix is to
+ * Don't use a virtual frame buffer.
+ * Make sure you load the NM256 module before the X server is
+On the F250, it is possible to force the driver to load properly even
+after the XFree86 server is started by doing:
+ insmod nm256.o buffertop=0x25a800
+This forces the audio buffers to the correct offset in screen RAM.
+Official WWW site
+The official site for the NM256 driver is:
+You should always be able to get the latest version of the driver there,
+and the driver will be supported for the foreseeable future.
+Z505S/Z505SX on-board Ethernet
+If you're using the on-board Ethernet Pro/100 ethernet support on the Z505
+series, I strongly encourage you to download the latest eepro100 driver from
+Donald Becker's site:
+There was a reported problem on the Z505SX that if the ethernet
+interface is disabled and reenabled while the sound driver is loaded,
+the machine would lock up. I have included a workaround that is
+working satisfactorily. However, you may occasionally see a message
+about "Releasing interrupts, over 1000 bad interrupts" which indicates
+that the workaround is doing its job.
+PCMCIA and the Z505S/Z505SX/Z505DX
+There is also a known problem with the Sony Z505S and Z505SX hanging
+if a PCMCIA card is inserted while the ethernet driver is loaded.
+This is caused by tons of spurious IRQ 9s, probably generated from the
+PCMCIA or ACPI bridges. There is currently no fix for the problem,
+and the only known workaround is to disable the ethernet interface
+before inserting or removing a PCMCIA card.
+First, I want to thank everyone (except NeoMagic of course) for their
+generous support and encouragement. I'd like to list everyone's name
+here that replied during the development phase, but the list is
+I will be rather unfair and single out a few people, however:
+ Justin Maurer, for being the first random net.person to try it,
+ and for letting me login to his Z505SX to get it working there
+ Edi Weitz for trying out several different versions, and giving
+ me a lot of useful feedback
+ Greg Rumple for letting me login remotely to get the driver
+ functional on the 256ZX, for his assistance on tracking
+ down all sorts of random stuff, and for trying out Accel-X
+ Zach Brown, for the initial AC97 mixer interface design
+ Jeff Garzik, for various helpful suggestions on the AC97
+Versions prior to 0.3 (aka `noname') had problems with weird artifacts
+in the output and failed to set the recording rate properly. These
+problems have long since been fixed.
+Versions prior to 0.5 had problems with clicks in the output when
+anything other than 16-bit stereo sound was being played, and also had
+periodic clicks when recording.
+Version 0.7 first incorporated support for the NM256ZX chipset, which
+is found on some Dell Latitude laptops (the CPt, and apparently
+some CPi models as well). It also included the generic AC97
+Version 0.75 renamed all the functions and files with slightly more
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