block: kill ISA_DMA_THRESHOLD usage
block uses ISA_DMA_THRESHOLD for BLK_BOUNCE_ISA. Only SCSI uses
ISA_DMA_THRESHOLD for ancient drivers with non-zero
unchecked_isa_dma. Nowadays drivers (and subsystems) use dma_mask
properly instead of ISA_DMA_THRESHOLD.
Documentation/scsi/scsi_mid_low_api.txt says:
unchecked_isa_dma - 1=>only use bottom 16 MB of ram (ISA DMA addressing
restriction), 0=>can use full 32 bit (or better) DMA
address space
So block simply uses DMA_BIT_MASK(24) for BLK_BOUNCE_ISA for SCSI.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b8224ea..d7ae241 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -712,7 +712,7 @@
#define BLK_BOUNCE_HIGH -1ULL
#endif
#define BLK_BOUNCE_ANY (-1ULL)
-#define BLK_BOUNCE_ISA (ISA_DMA_THRESHOLD)
+#define BLK_BOUNCE_ISA (DMA_BIT_MASK(24))
/*
* default timeout for SG_IO if none specified