Re: [PATCH] Re: 2.6.26-rc1 regression: ISA DMA broken (bisected)

[Rene Herman]

On 30-05-08 23:43, Bjorn Helgaas wrote:

> On Friday 30 May 2008 03:15:57 pm Rene Herman wrote:

> > It gets uglier. ALSA ISA drivers (for cards that exist both as legacy 
> > and as ISAPnP at least) keep a merged legacy/isapnp model; PnP is used 
> > mostly for initializing global variables that the same old legacy probe 
> > routines then reference. This means that beyond that global resource 
> > init step the specific struct device is no longer available. Without 
> > restructuring too many things really only fixable through other hacks 
> > again such as a global dma_dev[] array or some such.
> >
> >  From the viewpoint of PnP itself setting the dma_mask for a pnp_card (a 
> > pnp_dev collection) makes isolated sense so if no objections, I'll 
> > submit the attached after all. From the ALSA side we'd then pass the 
> > card dev (which we'd also do for isa_dev) and keep in mind that we might 
> > want to get more specific if over time structure permits it.
> >
> > struct snd_pcm already has its own struct device * which would be the 
> > right one here but it's setting that which gets ugly...
>
> Looks good to me.  It does sound like a lot of work and possibly
> more risk than it's worth to fix up some of this stuff.

Fairly invasive at least. The good thing though is that with the recent 
pnp_manual_config_dev() removal the PnP drivers have no actual need/use 
for this global variable model anymore and now I have a great excuse for 
rewriting them. That can happen one at a time though...

> I do still wonder whether any non-x86 architectures need similar
> fixes in dma_alloc_coherent(), i.e., check for dev==NULL and fall
> back to a 24-bit DMA mask.

Hrmmpf. Good question. In sound/isa, we've had a but of alpha spottyness 
over time but nothing which would seem to be related.

> Acked-by: Bjorn Helgaas <bjorn.helgaas@xxxxxx>

Thanks. I'll assume Andrew picks it up from the CC...

Rene.
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