linux-kernel - [PATCH 4/4] sdhci-of: Cleanup eSDHC's set

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Message-ID: <20090807165024.GC524@oksana.dev.rtsoft.ru>
Date:	Fri, 7 Aug 2009 20:50:24 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Pierre Ossman <pierre@...man.eu>,
	Kumar Gala <galak@...nel.crashing.org>,
	Ben Dooks <ben@...ff.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	linux-kernel@...r.kernel.org, sdhci-devel@...ts.ossman.eu,
	linuxppc-dev@...abs.org
Subject: [PATCH 4/4] sdhci-of: Cleanup eSDHC's set_clock() a little bit

- Get rid of incomprehensible "if { for { if } }" construction for the
  exponential divisor calculation. The first if statement isn't correct
  at all, since it should check for "host->max_clk / pre_div / 16 >
  clock". The error doesn't cause any bugs because the check in the for
  loop does the right thing, and so the outer check becomes useless;

- For the linear divisor do the same: a single while statement is more
  readable than for + if construction;

- Add dev_dbg() that prints desired and actual clock frequency.

Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
---
 drivers/mmc/host/sdhci-of.c |   19 ++++++++-----------
 1 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of.c b/drivers/mmc/host/sdhci-of.c
index b6ff2e8..bbdd468 100644
--- a/drivers/mmc/host/sdhci-of.c
+++ b/drivers/mmc/host/sdhci-of.c
@@ -120,8 +120,8 @@ static void esdhc_writeb(struct sdhci_host *host, u8 val, int reg)
 
 static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
 {
-	int div;
 	int pre_div = 2;
+	int div = 1;
 
 	clrbits32(host->ioaddr + ESDHC_SYSTEM_CONTROL, ESDHC_CLOCK_IPGEN |
 		  ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN | ESDHC_CLOCK_MASK);
@@ -129,17 +129,14 @@ static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
 	if (clock == 0)
 		goto out;
 
-	if (host->max_clk / 16 > clock) {
-		for (; pre_div < 256; pre_div *= 2) {
-			if (host->max_clk / pre_div < clock * 16)
-				break;
-		}
-	}
+	while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
+		pre_div *= 2;
 
-	for (div = 1; div <= 16; div++) {
-		if (host->max_clk / (div * pre_div) <= clock)
-			break;
-	}
+	while (host->max_clk / pre_div / div > clock && div < 16)
+		div++;
+
+	dev_dbg(mmc_dev(host->mmc), "desired SD clock: %d, actual: %d\n",
+		clock, host->max_clk / pre_div / div);
 
 	pre_div >>= 1;
 	div--;
-- 
1.6.3.3
--
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