Commit ad1e597d authored Sep 22, 2009 by Anton Vorontsov Committed by Linus Torvalds Sep 23, 2009

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>

parent 8226a219

drivers/mmc/host/sdhci-of.c

+8 −11

Original line number	Diff line number	Diff line
		@@ -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--;