[alsa-devel] Getting Started on Alsa

Ash Willis ashwillis at programmer.net
Mon May 7 04:12:20 CEST 2007

> Thanks for the tips, Ash. I've found the Iwai document. Now there's some
> light reading. I take it that it's still relevant, even though it hasn't
> been updated since 2005.
I haven't actually read it since 2005 I'm afraid :) but I don't think
anything's changed that drastically. The fundamentals are all there.

> Yes, the cs46xx driver. That chip is in a lot of machines (at least ten
> ThinkPad models), and with this bug nobody running Alsa likes Linux very
> much.

Yeah, it's a pretty poor show that this bug has existed for so long.
Let's hope you can zap it!

> Is there some (handy) way to dump the registers from DOS or Windows as a
> comparison?

Well, that depends. I'm not familiar with the hardware. There's a Windows
program called PCItree. It allows you to view the current status of the
ioport of a chosen device. Now, that's pretty handy if the regs for the card
are mapped directly onto the io port. It's usually the case though, I think,
that the registers aren't just mapped on and you'll need to query the card.
If they're not mapped onto the io port (and forgive me again - not familiar
with this chip) then you could use a debugger such as Numega SoftIce to
manually issue queries to find out the contents of the registers. Sounds like
a happy fun time. Writing the code to do a reg dump might be fun too.
You may also want to use a debugger/disassembler with Windows (or other)
drivers in order to find out what those drivers do to the card on resume.

> For development: Since the drivers go into the kernel, I should be able to
> find a page on getting a development environment set up... right? I'm

You don't need to mess with the kernel as ALSA is available as a package.
All you really need is the latest copy of alsa-driver and a compiler and
you're good to go.



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