[PATCH v2 3/3] scsi: ufs: Enable DMA clustering

[Bart Van Assche <bvanassche@acm.org>]

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 "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 4dd4130a722f ("scsi: make sure all drivers set the
  use_clustering flag") set the .use_clustering flag.
* Commit 4af14d113bcf ("scsi: remove the use_clustering flag") removed
  the use_clustering flag and set the dma_boundary parameter instead.

Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Kiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufshcd.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 5fdbc983ce2e..d28b44a1ffcf 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8460,7 +8460,6 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.max_host_blocked	= 1,
 	.track_queue_depth	= 1,
 	.sdev_groups		= ufshcd_driver_groups,
-	.dma_boundary		= PAGE_SIZE - 1,
 	.rpm_autosuspend_delay	= RPM_AUTOSUSPEND_DELAY_MS,
 };