linux-kernel - [PATCH] DMA: ste_dma40: use a power of 2 check

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Date:	Wed, 18 Sep 2013 09:33:08 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	linux-kernel@...r.kernel.org
cc:	"Koul, Vinod" <vinod.koul@...el.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] DMA: ste_dma40: use a power of 2 check

dst_addr_width and src_addr_width should be a power of 2. Currently the 
driver checks, that they both lie between 1 and 8 and that they are eqal 
to 1 or even. This however leaves an invalid value of 6 uncaught. Use an 
explicit power of 2 check instead.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@...il.com>
---

Compile tested only. I think 6 is an invalid value in this case, and since 
you check for odd calues, it seems to me that any value can be supplied 
here, so, looks like a power of 2 test is a better match for this.

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 82d2b97..3d5e4ee 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -14,6 +14,7 @@
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/log2.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/err.h>
@@ -2796,8 +2797,8 @@ static int d40_set_runtime_config(struct dma_chan *chan,
 	    src_addr_width >  DMA_SLAVE_BUSWIDTH_8_BYTES   ||
 	    dst_addr_width <= DMA_SLAVE_BUSWIDTH_UNDEFINED ||
 	    dst_addr_width >  DMA_SLAVE_BUSWIDTH_8_BYTES   ||
-	    ((src_addr_width > 1) && (src_addr_width & 1)) ||
-	    ((dst_addr_width > 1) && (dst_addr_width & 1)))
+	    !is_power_of_2(src_addr_width) ||
+	    !is_power_of_2(dst_addr_width))
 		return -EINVAL;
 
 	cfg->src_info.data_width = src_addr_width;
--
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