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 Cc: Takashi Iwai tiwai@suse.de Cc: Alan Cox alan@lxorguk.ukuu.org.uk --- drivers/base/isa.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/base/isa.c b/drivers/base/isa.c index d222239..efd5775 100644 --- a/drivers/base/isa.c +++ b/drivers/base/isa.c @@ -7,6 +7,7 @@ #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 = { @@ -141,6 +142,9 @@ int isa_register_driver(struct isa_driver *isa_driver, unsigned int ndev) 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);