Current implementation of sdhci_s3c_consider_clock() is highly inefficient due to multiple integer divisions by variable performed in a loop. Since only divisors that are powers of two are considered, this patch replaces them with respective shifts, removing all the integer divisions.
Signed-off-by: Tomasz Figa <[email protected]> --- drivers/mmc/host/sdhci-s3c.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/mmc/host/sdhci-s3c.c b/drivers/mmc/host/sdhci-s3c.c index 6debda9..52770d5 100644 --- a/drivers/mmc/host/sdhci-s3c.c +++ b/drivers/mmc/host/sdhci-s3c.c @@ -144,7 +144,7 @@ static unsigned int sdhci_s3c_consider_clock(struct sdhci_s3c *ourhost, { unsigned long rate; struct clk *clksrc = ourhost->clk_bus[src]; - int div; + int shift; if (!clksrc) return UINT_MAX; @@ -160,15 +160,15 @@ static unsigned int sdhci_s3c_consider_clock(struct sdhci_s3c *ourhost, rate = clk_get_rate(clksrc); - for (div = 1; div < 256; div *= 2) { - if ((rate / div) <= wanted) + for (shift = 0; shift < 8; ++shift) { + if ((rate >> shift) <= wanted) break; } dev_dbg(&ourhost->pdev->dev, "clk %d: rate %ld, want %d, got %ld\n", - src, rate, wanted, rate / div); + src, rate, wanted, rate >> shift); - return wanted - (rate / div); + return wanted - (rate >> shift); } /** -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
