On Mon, 18 Feb 2002, Takashi Iwai wrote:
> At Sun, 17 Feb 2002 10:29:20 +0100 (CET),
> Jaroslav wrote:
> >
> > On Sat, 16 Feb 2002, [iso-8859-1] Chris Rankin wrote:
> >
> > > Hi,
> > >
> > > I saw from the CVS ChangeLog that ALSA is moving away
> > > from the deprecated virt_to_bus() to the new
> > > pci_allocate_consistent() system calls. Unfortunately,
> > > this is causing problems for my ISA DMA sound driver
> > > (CS4231 / MPU401 based). I have currently "fixed"
> > > things by #undef-ing the ISA_USE_PCI_ALLOC in
> > > core/pcm_memory.c. Once I do this, I get sound out of
> > > my speakers again.
> > >
> > > My soundcard also needs a DMA-able buffer so that it
> > > can upload its firmware. Previously, I used
> > > snd_malloc_pages(), and I tried changing this to
> > > snd_malloc_isa_pages(). However, you don't export this
> > > function, and even when I cut-and-pasted it into the
> > > source file, the firmware wouldn't upload until I used
> > > the virt_to_bus()-based compatibility version.
> > >
> > > It would probably be a good idea to export the
> > > following functions:
> > >
> > > snd_malloc_pci_pages()
> > > snd_malloc_isa_pages()
> > > snd_free_pci_pages()
> > > snd_free_isa_pages()
> > >
> > > Does anyone have any idea why
> > > pci_allocate_consistent() isn't working here, please?
> >
> > Using pci_allocate_consistent() for ISA DMA allocation routines is
> > definitely a bad idea. I added snd_malloc_isa_pages() code as you
> > suggested to snd.o (it seems that it's good to abstract such bus specific
> > allocation routines).
>
> I don't think it's so bad to use pci_allocate_consistent(). It gives
> the only generic way to get DMA buffer allocation over all
> architectures without virt_to_bus. If it doesn't work well, it should
> be a bug of this function..
I verified the contents of pci_allocate_consistent() and I agree that it
should work at least for i386 and alpha architectures so I reverted back
your code.
> Anyway, yes, it would be better to use a generic function until the
> kernel function is fixed. Thanks.
>
> BTW, use of GFP_KERNEL for a large DMA buffer is safe on 2.4 too?
> For PCI buffers, when a module tries to allocate large memory areas
> with GFP_KERNEL, it stays blocking (and waiting for the enough space)
> and even more badly it cannot be killed.
I removed dma_flags from isa pages allocation routines. We use
GFP_ATOMIC|GFP_DMA like pci_allocate_consistent(). I'm not only sure about
2.2 kernels, but it's easy to fix this problem.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project http://www.alsa-project.org
SuSE Linux http://www.suse.com
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