[alsa-devel] [PATCH] opti931: additional check for OPL3 device
rene.herman at gmail.com
Mon Sep 17 12:10:12 CEST 2007
On 09/17/2007 10:14 AM, Clemens Ladisch wrote:
> Krzysztof Helt wrote:
>> Should the OPL4 detection has the same fallback or just all Opti cards
>> should search the FM chip at the range + 8 address?
> It appears a fallback shoudn't be needed because the chip always returns
> a range suitable for an OPL4.
> Since an OPL3 range is never larger than 8 bytes, and OPL4 needs 16
> bytes, we could add 8 to get the FM address _if_ the range is at least 16
> bytes; thus we are safe even if a chip publishes an OPL3-only range.
At least 16 won't do -- the OPTi chip provides a 12-byte range. More than 8
would work, but just +8 is fine. I have all OPTi ISA-PnP chips (924, 925,
931, 933) and more aren't going to be produced. The 0x380 base is what it
calls the OPL4Base and ALBase (AdLib) is at 0x388.
The chip can defer to external FM it seems, but even if there are OPTi/OPL4
combo's out there in the wild (I sort of doubt it) the driver's just doing
opl3 anyway. ie, still needs just the +8.
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