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Date: Wed, 23 Nov 2011 00:34:28 +0100 (CET)
From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
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To: Andrew Morton <akpm@linux-foundation.org>
cc: Andrei Warkentin <andreiw@vmware.com>, linux-kernel@vger.kernel.org,
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        Eddie Wai <eddie.wai@broadcom.com>,
        Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
Subject: Re: [PATCH] include/log2.h: Fix rounddown_pow_of_two(1)
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On Thu, 17 Nov 2011, Andrew Morton wrote:

[snip]

> drivers/mmc/host/sh_mmcif.c unnecessarily uses __rounddown_pow_of_two()
> then feeds the result into ilog2() in an apparent attempt to
> reimplement fls().

Yeah, I was wondering too, but wasn't sufficiently motivated to patch 
it;-) I'll test this "obvious" patch tomorrow and submit then:

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index c021482..824fee5 100644
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -16,6 +16,7 @@
  *
  */
 
+#include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
@@ -386,7 +387,7 @@ static void sh_mmcif_clock_control(struct sh_mmcif_host *host, unsigned int clk)
 		sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_SUP_PCLK);
 	else
 		sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR &
-			(ilog2(__rounddown_pow_of_two(host->clk / clk)) << 16));
+				((fls(host->clk / clk) - 1) << 16));
 
 	sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_ENABLE);
 }

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/