[PATCH] V2 2.6.35 libata support for > 512 byte sectors (e.g. 4K Native)
From: Grant Grundler
Date: Tue Aug 17 2010 - 13:57:09 EST
Attached patch enables my x86 machine to recognize and talk to a
"Native 4K" SATA device.
When I started working on this, I didn't know Matthew Wilcox had
posted a similar patch 2 years ago:
http://git.kernel.org/?p=linux/kernel/git/willy/ata.git;a=shortlog;h=refs/heads/ata-large-sectors
Gwendal Grignou pointed me at the the above code and small portions of
this patch include Matthew's work. That's why Mathew is first on the
"Signed-off-by:". I've NOT included his use of a bitmap to determine
512 vs Native for ATA command block size - just used a simple table.
And bugs are almost certainly mine.
Lastly, the patch has been tested with a native 4K 'Engineering
Sample' drive provided by Hitachi GST.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Signed-off-by: Grant Grundler <grundler@xxxxxxxxxx>
Reviewed-by: Gwendal Grignou <gwendal@xxxxxxxxxx>
----
V1: Gwendal reviewed had concerns about dev->sdev->sector_size which
seems to be ok.
V2: Matthew Wilcox suggested:
o remove comment about Big Endian (already handled)
o use "scmd->device->sector_size" instead of "dev->sdev->sector_size"
o ata_cmd_ioctl() does PIO data IN and thus should use native size.
o add "safe for large sectors" flag in the case that a
controller can't tolerate >512byte sector commands.
I did NOT add such a flag since I think the right answer would
be "Don't attach a Native 4K block device to that controller" - it
just won't work.
Tejun Heo (and I) prefer to leave ata_cmd_ioctl() hard coded to
512 byte since this ioctl is "should probably be deprecated one day".
thanks,
grant
[ patch NOT inlined because gmail will word-wrap and make a mess of
it. Please use attached file.]
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