+ drivers-scsi-53c700c-remove-dma_is_consistent-usage.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     drivers/scsi/53c700.c: remove dma_is_consistent usage
has been added to the -mm tree.  Its filename is
     drivers-scsi-53c700c-remove-dma_is_consistent-usage.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: drivers/scsi/53c700.c: remove dma_is_consistent usage
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

This driver is the only user of dma_is_consistent().  We plan to remove
this API.

The driver uses the API in the following way:

BUG_ON(!dma_is_consistent(hostdata->dev, pScript) && L1_CACHE_BYTES < dma_get_cache_alignment());

The above code tries to see if L1_CACHE_BYTES is greater than
dma_get_cache_alignment() on sysmtes that can not allocate coherent memory
(some old systems can't).

James Bottomley explained that this is necessary because the driver packs
the set of mailboxes into a single coherent area and separates the
different usages by a L1 cache stride.  So it's fatal if the dma coherence
stride is greater than the L1 cache size.

He also pointed out that we can kill this checking because we don't hit
this BUG_ON on all architectures that actually use the driver.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/scsi/53c700.c |    3 ---
 1 file changed, 3 deletions(-)

diff -puN drivers/scsi/53c700.c~drivers-scsi-53c700c-remove-dma_is_consistent-usage drivers/scsi/53c700.c
--- a/drivers/scsi/53c700.c~drivers-scsi-53c700c-remove-dma_is_consistent-usage
+++ a/drivers/scsi/53c700.c
@@ -309,9 +309,6 @@ NCR_700_detect(struct scsi_host_template
 	hostdata->msgin = memory + MSGIN_OFFSET;
 	hostdata->msgout = memory + MSGOUT_OFFSET;
 	hostdata->status = memory + STATUS_OFFSET;
-	/* all of these offsets are L1_CACHE_BYTES separated.  It is fatal
-	 * if this isn't sufficient separation to avoid dma flushing issues */
-	BUG_ON(!dma_is_consistent(hostdata->dev, pScript) && L1_CACHE_BYTES < dma_get_cache_alignment());
 	hostdata->slots = (struct NCR_700_command_slot *)(memory + SLOTS_OFFSET);
 	hostdata->dev = dev;
 
_

Patches currently in -mm which might be from fujita.tomonori@lab.ntt.co.jp are

linux-next.patch
scsi-add-__init-__exit-macros-to-ibmvstgtc.patch
dma-mapping-rename-arch_kmalloc_minalign-to-arch_dma_minalign.patch
dma-mapping-unify-dma_get_cache_alignment-implementations.patch
dma-mapping-parisc-set-arch_dma_minalign.patch
drivers-scsi-53c700c-remove-dma_is_consistent-usage.patch
dma-mapping-remove-dma_is_consistent-api.patch