[PATCH] mxs-mmc: fix clock rate setting

Koen Beel
2011-06-30T10:13:35Z

Fix clock rate setting on mxs-mmc driver.
Previously, if div2 was zero the value for TIMING_CLOCK_RATE would
have been 255 instead of 0.
Also the limits for div1 (TIMING_CLOCK_DIVIDE) and div2
(TIMING_CLOCK_RATE + 1) where not correctly defined.

Can easily be reproduced on mx23evk: default clock for high speed sdio
cards is 50 MHz. With a SSP_CLK of 28.8 MHz (default), this resulted in
an actual clock rate of about 56 kHz.

Signed-off-by: Koen Beel <koen.beel.barco <at> gmail.com>
---
drivers/mmc/host/mxs-mmc.c |   12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
index 99d39a6..3575330 100644
--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -570,22 +570,22 @@ static void mxs_mmc_set_clk_rate(struct
mxs_mmc_host *host, unsigned int rate)
ssp_rate = clk_get_rate(host->clk);
-   for (div1 = 2; div1 < 254; div1 += 2) {
+   for (div1 = 2; div1 <= 254; div1 += 2) {
div2 = ssp_rate / rate / div1;
-       if (div2 < 0x100)
+       if (div2 <= 256)
break;
}
-   if (div1 >= 254) {
+   if (div1 > 254) {
dev_err(mmc_dev(host->mmc),
"%s: cannot set clock to %d\n", __func__, rate);
return;
}
if (div2 == 0)
-       bit_rate = ssp_rate / div1;
-   else
-       bit_rate = ssp_rate / div1 / div2;
+       div2 = 1;
+
+   bit_rate = ssp_rate / div1 / div2;
val = readl(host->base + HW_SSP_TIMING);
val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE);
--
1.7.4.1