Fix for PPC audio devices that can't reendianize samples

[Geert Uytterhoeven]

On Sun, 12 Aug 2001, Iain Sandoe wrote:
> On Sat, Aug 11, 2001,  Geert Uytterhoeven wrote:
> > On Fri, 10 Aug 2001, Iain Sandoe wrote:
> >> > The attached patch adds code to drivers/sound/dmasound/trans_16.c to
> >> > byteswap little-endian audio samples for hardware that needs it (like the
> >> > DACA audio chip in the iBook and iBook FireWire), and also marks the DACA
> >> > in the iBook FireWire as being unable to handle little-endian audio
> >> > samples (in dmasound_awacs.c).
> >>
> >> we've been round this loop ;-)))
> >>
> >> the reason that the byte-swap code was taken out of trans_16.c is that it
> >> will never be allowed into the kernel.
> >
> > And we'll have to remove the current byteswap code in the kernel (there still
> > is some).
>
> Well, actually, I'd like to lose all the translation stuff (rate conversion,
> format conversion etc.).  This belongs in User-Land and is preventing me
> from implementing mmio (which would be useful for the more serious
> applications).

Sorry, that's what I meant: all translation code.

> My main problems atm are:
>
> (a) working out what to do about mksound() - this is messy as it is and
> needs fixing in order to deal with DACA & Tumbler (it fiddles with the H/W
> which makes it chip-specific at present)...

Yes, mksound() messes with the sound hardware on most m68k boxes too.

Perhaps we should make it more generic, and move it to dmasound?
The disadvantage is that you can't get system beep anymore without dmasound.

> (b) wondering if losing all that stuff is going to be acceptable to the m68k
> ports (or whether we will end up having a PPC-specific driver).

If the removal of the translation stuff is imposed from upstream (Linus/Alan),
we must comply. Once user space is fixed, it should work everywhere. So m68k
will benefit from the work done on PPC (once in a time it was vice versa :-)

> (c) not having any time ... (but that's an old problem) ...

Idem ditto.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/