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Subject[PATCH 6/7] 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>
---
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 87aaf4b..048bc01 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--;
--
1.6.3.3


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