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Clip the upper end to 31MHz for slow clock speeds. On faster

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machines, we wind up with a 66MHz clock, which is too fast.
This commit is contained in:
Warner Losh 2012-08-28 14:19:10 +00:00
parent 10f0ab3933
commit d7f8f1facd
1 changed files with 6 additions and 5 deletions
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11
sys/arm/at91/at91_mci.c
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@ -557,10 +557,10 @@ at91_mci_update_ios(device_t brdev, device_t reqdev)
* Calculate our closest available clock speed that doesn't exceed the
* requested speed.
*
* If the master clock is greater than 50MHz and the requested bus
* speed is 25mhz and the use_30mhz flag is on, set clkdiv to zero to
* get a master_clock / 2 (25-30MHz) MMC/SD clock rather than settle for
* the next lower click (12-15MHz). See comments near the top of the
* If the master clock is 50MHz-62MHz and the requested bus speed is
* 25mhz and the use_30mhz flag is on, set clkdiv to zero to get a
* master_clock / 2 (25-31MHz) MMC/SD clock rather than settle for the
* next lower click (12.5-15.5MHz). See comments near the top of the
* file for more info.
*
* Whatever we come up with, store it back into ios->clock so that the
@ -572,7 +572,8 @@ at91_mci_update_ios(device_t brdev, device_t reqdev)
} else {
WR4(sc, MCI_CR, MCI_CR_MCIEN|MCI_CR_PWSEN);
if (sc->use_30mhz && ios->clock == 25000000 &&
at91_master_clock > 50000000)
at91_master_clock > 50000000 &&
at91_master_clock < 62000000)
clkdiv = 0;
else if ((at91_master_clock % (ios->clock * 2)) == 0)
clkdiv = ((at91_master_clock / ios->clock) / 2) - 1;