diff mbox series

[RFC,v7,4/5] block: add a helper function to merge the segments

Message ID 1561020610-953-5-git-send-email-yoshihiro.shimoda.uh@renesas.com (mailing list archive)
State New, archived
Headers show
Series treewide: improve R-Car SDHI performance | expand

Commit Message

Yoshihiro Shimoda June 20, 2019, 8:50 a.m. UTC 
This patch adds a helper function whether a queue can merge
the segments by the DMA MAP layer (e.g. via IOMMU).

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 block/blk-settings.c   | 22 ++++++++++++++++++++++
 include/linux/blkdev.h |  2 ++
 2 files changed, 24 insertions(+)

Comments

Christoph Hellwig June 24, 2019, 6:22 a.m. UTC | #1 
> +bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
> +				       struct device *dev)
> +{
> +	unsigned long boundary = dma_get_merge_boundary(dev);
> +
> +	if (!boundary)
> +		return false;
> +
> +	/* No need to update max_segment_size. see blk_queue_virt_boundary() */
> +	blk_queue_virt_boundary(q, boundary);
> +
> +	return true;

I'd skip that empty line here, but that is way into nitpick territory.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 45f2c52..6a78ea0 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -4,6 +4,7 @@ 
  */
 #include <linux/bio.h>
 #include <linux/blkdev.h>
+#include <linux/dma-mapping.h>
 #include <linux/gcd.h>
 #include <linux/gfp.h>
 #include <linux/init.h>
@@ -831,6 +832,27 @@  void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
 }
 EXPORT_SYMBOL_GPL(blk_queue_write_cache);
 
+/**
+ * blk_queue_can_use_dma_map_merging - configure queue for merging segments.
+ * @q:		the request queue for the device
+ * @dev:	the device pointer for dma
+ *
+ * Tell the block layer about merging the segments by dma map of @q.
+ */
+bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
+				       struct device *dev)
+{
+	unsigned long boundary = dma_get_merge_boundary(dev);
+
+	if (!boundary)
+		return false;
+
+	/* No need to update max_segment_size. see blk_queue_virt_boundary() */
+	blk_queue_virt_boundary(q, boundary);
+
+	return true;
+}
+
 static int __init blk_settings_init(void)
 {
 	blk_max_low_pfn = max_low_pfn - 1;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 592669b..a7a839d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1091,6 +1091,8 @@  extern void blk_queue_dma_alignment(struct request_queue *, int);
 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
 extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);
+extern bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
+					      struct device *dev);
 
 /*
  * Number of physical segments as sent to the device.