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authorAnton Vorontsov <avorontsov@ru.mvista.com>2009-09-22 16:45:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 07:39:37 -0700
commitad1e597d4199ffcdee04b9fb402e45c5be6a5052 (patch)
tree55792614ebf09ff2d293a1f190979eede5066f8c /drivers/mmc
parent8226a219254bbcd20492df185f191a11a7a81dcd (diff)
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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@ru.mvista.com> Cc: Pierre Ossman <pierre@ossman.eu> Cc: Kumar Gala <galak@kernel.crashing.org> Cc: David Vrabel <david.vrabel@csr.com> Cc: Ben Dooks <ben@fluff.org> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: <linux-mmc@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/sdhci-of.c19
1 files changed, 8 insertions, 11 deletions
diff --git a/drivers/mmc/host/sdhci-of.c b/drivers/mmc/host/sdhci-of.c
index c8dab07..01ab916 100644
--- a/drivers/mmc/host/sdhci-of.c
+++ b/drivers/mmc/host/sdhci-of.c
@@ -121,8 +121,8 @@ 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);
@@ -130,17 +130,14 @@ 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--;