dma_alloc_coherent() on x86 currently takes a passed in NULL device
pointer to mean that it should allocate an ISA compatible (24-bit) buffer
which is a bit of a hack.
The ALSA ISA drivers are the main consumers of this but have a struct
device in fact readily available.
For the legacy drivers, this sets the device dma_mask in preparation for
using the actual device with the DMA API so as to eventually not need the
NULL hack in dma_alloc_coherent().
This does not fix a current bug -- 2.6.26-rc1 stumbled over the NULL hack
in dma_alloc_coherent() but this has already been fixed in commit
4a367f3a9dbf2e7ffcee4702203479809236ee6e by Takashi Iwai.
Signed-off-by: Rene Herman <rene.herman@gmail.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/dma-mapping.h>
#include <linux/isa.h>
static struct device isa_bus = {
isa_dev->dev.release = isa_dev_release;
isa_dev->id = id;
+ isa_dev->dev.coherent_dma_mask = DMA_24BIT_MASK;
+ isa_dev->dev.dma_mask = &isa_dev->dev.coherent_dma_mask;
+
error = device_register(&isa_dev->dev);
if (error) {
put_device(&isa_dev->dev);