[alsa-devel] [PATCH] ess1688: fix OPL3 port setting

[Krzysztof Helt]

On Mon, 26 Jan 2009 10:42:29 +0100
Takashi Iwai <tiwai at suse.de> wrote:

> At Sun, 25 Jan 2009 23:05:55 +0100,
> Rene Herman wrote:
> > 
> > On 25-01-09 21:10, Krzysztof Helt wrote:
> > 
> > > From: Krzysztof Helt <krzysztof.h1 at wp.pl>
> > > 
> > > The ess1688 driver uses the same port
> > > for PCM audio (SB compatible) and OPL3
> > > synthesis. It is wrong so allow to
> > > choose a correct port for OPL3 synthesis.
> > 
> > Only a very quick reply -- generally, the low 2 SB ports are indeed OPL3 
> > compatible (or was it just OPL2? ...)
> 
> All devices have separate OPL3 I/O ports.  So there must be a
> reason...
> 

The ESS 688 datasheet states that FM chip select signal (FMCSB) 
is activated when one of the port ranges: 
388H-389H, 2x8H-2x9H, 2x0H-2x3H
is selected. The current code may work on on the ESS 688. 
However, it obviously does not work with the ESS 1688 (bug #282).
The bug report states that the OPL3 synthesis works with the
OSS driver which chooses the 0x388 port for the OPL3.

My patch adds a new port setting so it is still possible to set
the fm_port value the same as the port value. No change here.
However, it allows setting different values to the port and the
fm_port setting if needed.

Takashi, please consider applying my patch to the alsa tree.

Regards,
Krzysztof

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