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    Jeff

    Garzik

   1999-2001

   Jeff Garzik

     This documentation is free software; you can redistribute

     it and/or modify it under the terms of the GNU General Public

     License as published by the Free Software Foundation; either

     version 2 of the License, or (at your option) any later

     version.

     This program is distributed in the hope that it will be

     useful, but WITHOUT ANY WARRANTY; without even the implied

     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

     See the GNU General Public License for more details.

     You should have received a copy of the GNU General Public

     License along with this program; if not, write to the Free

     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,

     MA 02111-1307 USA

     For more details see the file COPYING in the source

     distribution of Linux.

        The Via VT82C686A "super southbridge" chips contain

        AC97-compatible audio logic which features dual 16-bit stereo

        PCM sound channels (full duplex), plus a third PCM channel intended for use

        in hardware-assisted FM synthesis. The VIA VT8233/8235 extends this

        support to include six channel output and additional record

        facilities.

        The current Linux kernel audio driver for this family of chips

        supports audio playback and recording, but hardware-assisted

        FM features, and hardware buffer direct-access (mmap)

        support are not yet available.

        This driver supports any Linux kernel version after 2.4.10.

        Please send bug reports to the mailing list linux-via@gtf.org.

        To subscribe, e-mail majordomo@gtf.org with

        subscribe linux-via

        in the body of the message.

        To use this audio driver, select the

        CONFIG_SOUND_VIA82CXXX option in the section Sound during kernel configuration.

        Follow the usual kernel procedures for rebuilding the kernel,

        or building and installing driver modules.

        To make this driver the default audio driver, you can add the

        following to your /etc/conf.modules file:

        alias sound via82cxxx_audio

        Note that soundcore and ac97_codec support modules

        are also required for working audio, in addition to

        the via82cxxx_audio module itself.

        Describe the application you were using to play/record sound, and how

        to reproduce the problem.

        Obtain the via-audio-diag diagnostics program from

        http://sf.net/projects/gkernel/ and provide a dump of the

        audio chip's registers while the problem is occurring.  Sample command line:

        ./via-audio-diag -aps > diag-output.txt

        Define VIA_DEBUG at the beginning of the driver, then capture and email

        the kernel log output.  This can be viewed in the system kernel log (if

        enabled), or via the dmesg program.  Sample command line:

        dmesg > /tmp/dmesg-output.txt

        If you wish to increase the size of the buffer displayed by dmesg, then

        change the LOG_BUF_LEN macro at the top of linux/kernel/printk.c, recompile

        your kernel, and pass the LOG_BUF_LEN value to dmesg.  Sample command line with

        LOG_BUF_LEN == 32768:

        dmesg -s 32768 > /tmp/dmesg-output.txt

    Low volume

        Volume too low on many systems.  Workaround:  use mixer program

        such as xmixer to increase volume.

        Via for providing e-mail support, specs, and NDA'd source code.

        MandrakeSoft for providing hacking time.

        AC97 mixer interface fixes and debugging by Ron Cemer roncemer@gte.net.

        Rui Sousa rui.sousa@conexant.com, for bugfixing

        MMAP support, and several other notable fixes that resulted from

        his hard work and testing.

        Adrian Cox adrian@humboldt.co.uk, for bugfixing

        MMAP support, and several other notable fixes that resulted from

        his hard work and testing.

        Thomas Sailer for further bugfixes.

        Two /proc pseudo-files provide diagnostic information.  This is generally

        not useful to most users.  Power users can disable CONFIG_SOUND_VIA82CXXX_PROCFS,

        and remove the /proc support code.  Once

        version 2.0.0 is released, the /proc support code will be disabled by

        default.  Available /proc pseudo-files:

        /proc/driver/via/0/info

        /proc/driver/via/0/ac97

        This driver by default supports all PCI audio devices which report

        a vendor id of 0x1106, and a device id of 0x3058.  Subsystem vendor

        and device ids are not examined. The 8233 support covers all devices

        with a device id of 0x3059 and vendor id of 0x1106. Again subsystem

        ids are ignored as they usually hold the AC97 codec vendor information.

        GNU indent formatting options:

-kr -i8 -ts8 -br -ce -bap -sob -l80 -pcs -cs -ss -bs -di1 -nbc -lp -psl

        Via has graciously donated e-mail support and source code to help further

        the development of this driver.  Their assistance has been invaluable

        in the design and coding of the next major version of this driver.

        The Via audio chip apparently provides a second PCM scatter-gather

        DMA channel just for FM data, but does not have a full hardware MIDI

        processor.  I haven't put much thought towards a solution here, but it

        might involve using SoftOSS midi wave table, or simply disabling MIDI

        support altogether and using the FM PCM channel as a second (input? output?)

    Added VIA 8233/8235 support including six channel support. We don't

    yet support S/PDIF, EAPD, using the second DSP channel and FM channels

    as extra dsp devices, or the extra record channel. New features tested

    on a VIA EPIA-M kindly provided by VIA.

    DSP read/write bugfixes from Thomas Sailer.

    Add new PCI id for single-channel use of Via 8233.

    Other bug fixes, tweaks, new ioctls.

    Support for variable fragment size and variable fragment number (Rui

    Sousa)

    Fixes for the SPEED, STEREO, CHANNELS, FMT ioctls when in read &

    write mode (Rui Sousa)

    Mmaped sound is now fully functional. (Rui Sousa)

    Make sure to enable PCI device before reading any of its PCI

    config information. (fixes potential hotplug problems)

    Clean up code a bit and add more internal function documentation.

    AC97 codec access fixes (Adrian Cox)

    Big endian fixes (Adrian Cox)

    MIDI support (Adrian Cox)

    Detect and report locked-rate AC97 codecs.  If your hardware only

    supports 48Khz (locked rate), then your recording/playback software

    must upsample or downsample accordingly.  The hardware cannot do it.

    Use new pci_request_regions and pci_disable_device functions in

    kernel 2.4.6.

    Use VM_RESERVE when available, to eliminate unnecessary page faults.

    mmap bug fixes from Linus.

    Many more bug fixes.  mmap enabled by default, but may still be buggy.

    Uses new and spiffy method of mmap'ing the DMA buffer, based

    on a suggestion from Linus.

    Many bug fixes.  mmap enabled by default, but may still be buggy.

    Redesign and rewrite audio playback implementation.  (faster and smaller, hopefully)

    Implement recording and full duplex (DSP_CAP_DUPLEX) support.

    Make procfs support optional.

    Quick interrupt status check, to lessen overhead in interrupt

    sharing situations.

    Add mmap(2) support.  Disabled for now, it is still buggy and experimental.

    Surround all syscalls with a semaphore for cheap and easy SMP protection.

    Fix bug in channel shutdown (hardware channel reset) code.

    Remove unnecessary spinlocks (better performance).

    Eliminate "unknown AFMT" message by using a different method

    of selecting the best AFMT_xxx sound sample format for use.

    Support for realtime hardware pointer position reporting

    (DSP_CAP_REALTIME, SNDCTL_DSP_GETxPTR ioctls)

    Support for capture/playback triggering

    (DSP_CAP_TRIGGER, SNDCTL_DSP_SETTRIGGER ioctls)

    SNDCTL_DSP_SETDUPLEX and SNDCTL_DSP_POST ioctls now handled.

    Rewrite open(2) and close(2) logic to allow only one user at

    a time.  All other open(2) attempts will sleep until they succeed.

    FIXME: open(O_RDONLY) and open(O_WRONLY) should be allowed to succeed.

    Reviewed code to ensure that SMP and multiple audio devices

    are fully supported.

        Clean up interrupt handler output.  Fixes the following kernel error message:

        unhandled interrupt ...

        Convert documentation to DocBook, so that PDF, HTML and PostScript (.ps) output is readily

        available.

 Fix module unload bug where mixer device left registered

  after driver exit

 Rewrite via_set_rate to mimic ALSA basic AC97 rate setting

 Remove much dead code

 Complete spin_lock_irqsave -> spin_lock_irq conversion in via_dsp_ioctl

 Fix build problem in via_dsp_ioctl

 Optimize included headers to eliminate headers found in linux/drivers/sound

 Disable some overly-verbose debugging code

 Remove unnecessary sound locks

 Fix some ioctls for better time resolution

 Begin spin_lock_irqsave -> spin_lock_irq conversion in via_dsp_ioctl

 Completed rewrite of driver.  Eliminated SoundBlaster compatibility

  completely, and now uses the much-faster scatter-gather DMA engine.

!Idrivers/sound/via82cxxx_audio.c