From: Anton Vorontsov <avorontsov@xxxxxxxxxxxxx>
- 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@xxxxxxxxxxxxx>
Cc: Pierre Ossman <pierre@xxxxxxxxx>
Cc: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxx>
Cc: Ben Dooks <ben@xxxxxxxxx>
Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: <linux-mmc@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci-of.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff -puN drivers/mmc/host/sdhci-of.c~sdhci-of-cleanup-esdhcs-set_clock-a-little-bit drivers/mmc/host/sdhci-of.c
--- a/drivers/mmc/host/sdhci-of.c~sdhci-of-cleanup-esdhcs-set_clock-a-little-bit
+++ a/drivers/mmc/host/sdhci-of.c
@@ -121,8 +121,8 @@ static void esdhc_writeb(struct sdhci_ho
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
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--;
_
--
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