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>
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@ -121,8 +121,8 @@ static void esdhc_writeb(struct sdhci_host *host, u8 val, int reg)
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static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
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static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
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{
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{
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int div;
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int pre_div = 2;
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int pre_div = 2;
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int div = 1;
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clrbits32(host->ioaddr + ESDHC_SYSTEM_CONTROL, ESDHC_CLOCK_IPGEN |
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clrbits32(host->ioaddr + ESDHC_SYSTEM_CONTROL, ESDHC_CLOCK_IPGEN |
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ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN | ESDHC_CLOCK_MASK);
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ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN | ESDHC_CLOCK_MASK);
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@ -130,17 +130,14 @@ static void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
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if (clock == 0)
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if (clock == 0)
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goto out;
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goto out;
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if (host->max_clk / 16 > clock) {
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while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
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for (; pre_div < 256; pre_div *= 2) {
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pre_div *= 2;
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if (host->max_clk / pre_div < clock * 16)
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break;
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}
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}
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for (div = 1; div <= 16; div++) {
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while (host->max_clk / pre_div / div > clock && div < 16)
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if (host->max_clk / (div * pre_div) <= clock)
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div++;
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break;
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}
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dev_dbg(mmc_dev(host->mmc), "desired SD clock: %d, actual: %d\n",
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clock, host->max_clk / pre_div / div);
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pre_div >>= 1;
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pre_div >>= 1;
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div--;
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div--;
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