...which shows that in this environment GFP_KERNEL memory may be backed
by a 64-bit dma address. This breaks the driver's assumption that an
unsigned long should be able to contain the physical address for
descriptor memory. Switch to dma_addr_t which beyond being the right
size, is the true type for the data i.e. an io-virtual address
inidicating the engine's last processed descriptor.
[stable: 3.2+] Cc: <stable@vger.kernel.org> Reported-by: Jonathan Nieder <jrnieder@gmail.com> Reported-by: William Dauchy <wdauchy@gmail.com> Tested-by: William Dauchy <wdauchy@gmail.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>