Hello,
linux-2.6.35.3\drivers\spi\spi_mxs.c tries to set the maximum clock rate using the lines
rate = 1000 * ss->speed_khz / ss->divider / hz;
__raw_writel(BF_SSP_TIMING_CLOCK_DIVIDE(ss->divider) |
BF_SSP_TIMING_CLOCK_RATE(rate - 1),
ss->regs + HW_SSP_TIMING);
However this should round up the calculated rate variable otherwise the clock is set beyond the rate requested, e.g.
ss->speed_khz = 24000
ss->divider = 2
hz = 7000000 (requesting max rate of 7MHz)
==> rate = 1 (rounded down from 1.7)
==> SPI clock = 24000000 / (2 * (1+0)) = 12000000, i.e. 12MHz
This can be fixed in many ways. I did
if ((1000 * ss->speed_khz) > (rate * ss->divider * hz))
rate++; /* round up */
Matt.
