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Fix the clock divisor calc for imx6 sdcard bus speed.

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I don't know what alternate universe I was inhabiting when I wrote it
originally, but apparently the basic workings of mathematics were different
than in this universe.  I also can't explain how it ever worked, except "by
accident", because completely bogus values were being written into the
divisor register.
This commit is contained in:
ian 2015-12-18 01:25:30 +00:00
parent a12e9d2b9f
commit 7292e55261
1 changed files with 9 additions and 2 deletions
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11
sys/arm/freescale/imx/imx_sdhci.c
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@ -522,12 +522,19 @@ imx_sdhc_set_clock(struct imx_sdhci_softc *sc, int enable)
else
freq = sc->baseclk_hz / (2 * divisor);
for (prescale = 2; prescale < freq / prescale / 16;)
for (prescale = 2; freq < sc->baseclk_hz / (prescale * 16);)
prescale <<= 1;
for (divisor = 1; freq < freq / prescale / divisor;)
for (divisor = 1; freq < sc->baseclk_hz / (prescale * divisor);)
++divisor;
#ifdef DEBUG
device_printf(sc->dev,
"desired SD freq: %d, actual: %d; base %d prescale %d divisor %d\n",
freq, sc->baseclk_hz / (prescale * divisor), sc->baseclk_hz,
prescale, divisor);
#endif
prescale >>= 1;
divisor -= 1;