[PATCH 8/9] dw_dmac: introduce dwc_fast_fls()

[Andy Shevchenko]

There were three places where such function is used. We still avoid to use
native fls() because in one case it requires to use 64bit version which is
suboptimal in our case.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/dma/dw_dmac.c |   46 ++++++++++++++++++----------------------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index b2586bd..5d025d3 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -193,6 +193,21 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
 
 /*----------------------------------------------------------------------*/
 
+static inline unsigned int dwc_fast_fls(unsigned long long v)
+{
+	/*
+	 * We can be a lot more clever here, but this should take care
+	 * of the most common optimization.
+	 */
+	if (!(v & 7))
+		return 3;
+	else if (!(v & 3))
+		return 2;
+	else if (!(v & 1))
+		return 1;
+	return 0;
+}
+
 static void dwc_dump_chan_regs(struct dw_dma_chan *dwc)
 {
 	dev_err(chan2dev(&dwc->chan),
@@ -644,18 +659,7 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
 		return NULL;
 	}
 
-	/*
-	 * We can be a lot more clever here, but this should take care
-	 * of the most common optimization.
-	 */
-	if (!((src | dest  | len) & 7))
-		src_width = dst_width = 3;
-	else if (!((src | dest  | len) & 3))
-		src_width = dst_width = 2;
-	else if (!((src | dest | len) & 1))
-		src_width = dst_width = 1;
-	else
-		src_width = dst_width = 0;
+	src_width = dst_width = dwc_fast_fls(src | dest | len);
 
 	ctllo = DWC_DEFAULT_CTLLO(chan)
 			| DWC_CTLL_DST_WIDTH(dst_width)
@@ -755,14 +759,7 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 			mem = sg_dma_address(sg);
 			len = sg_dma_len(sg);
 
-			if (!((mem | len) & 7))
-				mem_width = 3;
-			else if (!((mem | len) & 3))
-				mem_width = 2;
-			else if (!((mem | len) & 1))
-				mem_width = 1;
-			else
-				mem_width = 0;
+			mem_width = dwc_fast_fls(mem | len);
 
 slave_sg_todev_fill_desc:
 			desc = dwc_desc_get(dwc);
@@ -822,14 +819,7 @@ slave_sg_todev_fill_desc:
 			mem = sg_dma_address(sg);
 			len = sg_dma_len(sg);
 
-			if (!((mem | len) & 7))
-				mem_width = 3;
-			else if (!((mem | len) & 3))
-				mem_width = 2;
-			else if (!((mem | len) & 1))
-				mem_width = 1;
-			else
-				mem_width = 0;
+			mem_width = dwc_fast_fls(mem | len);
 
 slave_sg_fromdev_fill_desc:
 			desc = dwc_desc_get(dwc);
-- 
1.7.10

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/