All UFS host controllers support DMA clustering. Hence enable DMA
clustering.
Notes:
- The max_segment_size parameter implements the 256 KiB limit for the
PRDT. The dma_boundary parameter represents a boundary that must not be
crossed by DMA scatter/gather lists. I'm not aware of any restrictions
on DMA scatter/gather lists in the UFSHCI specification other than the
256 KiB limit for the PRDT and the 32-bit address restriction for
controllers that only support 32-bits DMA. The latter restriction is
already handled by ufshcd_set_dma_mask().
- Without patch "scsi: ufs: exynos: Fix the maximum segment size", this
patch breaks support for the Exynos controller.
The history of the dma_boundary parameter in the UFS driver is as
follows:
* The initial UFS driver did not set the dma_boundary parameter.
* Commit 4dd4130a72 ("scsi: make sure all drivers set the use_clustering
flag") set the .use_clustering flag.
* Commit 4af14d113b ("scsi: remove the use_clustering flag") removed the
use_clustering flag and set the dma_boundary parameter instead.
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Kiwoong Kim <kwmad.kim@samsung.com>
Change-Id: I7a14065dee3278b93f51e66b132dd2ffbc3020c4
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from commit 13f87983fb91454e4a534bb41b5b2b43afe97798 git://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git for-next)
Signed-off-by: Bart Van Assche <bvanassche@google.com>
c4e9d151d5