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Commit d982dcdc authored by Koen Beel's avatar Koen Beel Committed by Chris Ball
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mmc: mxs-mmc: fix clock rate setting 



Fix clock rate setting in the mxs-mmc driver. Previously, if div2 was 0
then the value for TIMING_CLOCK_RATE would have been 255 instead of 0.
The limits for div1 (TIMING_CLOCK_DIVIDE) and div2 (TIMING_CLOCK_RATE+1)
were also 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.  Tested on mx23evk.

Signed-off-by: default avatarKoen Beel <koen.beel@barco.com>
Reviewed-by: default avatarWolfram Sang <w.sang@pengutronix.de>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 162f43e3

drivers/mmc/host/mxs-mmc.c

+14 −16
Original line number Diff line number Diff line
@@ -564,40 +564,38 @@ static void mxs_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) 


static void mxs_mmc_set_clk_rate(struct mxs_mmc_host *host, unsigned int rate)

{

	unsigned int ssp_rate, bit_rate;

	u32 div1, div2;

	unsigned int ssp_clk, ssp_sck;

	u32 clock_divide, clock_rate;

	u32 val;



	ssp_rate = clk_get_rate(host->clk);

	ssp_clk = clk_get_rate(host->clk);



	for (div1 = 2; div1 < 254; div1 += 2) {

		div2 = ssp_rate / rate / div1;

		if (div2 < 0x100)

	for (clock_divide = 2; clock_divide <= 254; clock_divide += 2) {

		clock_rate = DIV_ROUND_UP(ssp_clk, rate * clock_divide);

		clock_rate = (clock_rate > 0) ? clock_rate - 1 : 0;

		if (clock_rate <= 255)

			break;

	}



	if (div1 >= 254) {

	if (clock_divide > 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;

	ssp_sck = ssp_clk / clock_divide / (1 + clock_rate);



	val = readl(host->base + HW_SSP_TIMING);

	val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE);

	val |= BF_SSP(div1, TIMING_CLOCK_DIVIDE);

	val |= BF_SSP(div2 - 1, TIMING_CLOCK_RATE);

	val |= BF_SSP(clock_divide, TIMING_CLOCK_DIVIDE);

	val |= BF_SSP(clock_rate, TIMING_CLOCK_RATE);

	writel(val, host->base + HW_SSP_TIMING);



	host->clk_rate = bit_rate;

	host->clk_rate = ssp_sck;



	dev_dbg(mmc_dev(host->mmc),

		"%s: div1 %d, div2 %d, ssp %d, bit %d, rate %d\n",

		__func__, div1, div2, ssp_rate, bit_rate, rate);

		"%s: clock_divide %d, clock_rate %d, ssp_clk %d, rate_actual %d, rate_requested %d\n",

		__func__, clock_divide, clock_rate, ssp_clk, ssp_sck, rate);

}



static void mxs_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)