From 4f425280fa718a88c436d16d88c2efd6a998943a Mon Sep 17 00:00:00 2001 From: =?utf8?q?Beno=C3=AEt=20Th=C3=A9baudeau?= Date: Wed, 3 May 2017 11:59:03 +0200 Subject: [PATCH] mmc: fsl_esdhc: Allow all supported prescaler values MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On i.MX, SYSCTL.SDCLKFS may be set to 0 in order to make the SD clock frequency prescaler divide by 1 in SDR mode. In DDR mode, the prescaler can divide by up to 512. Allow both of these settings. The maximum SD clock frequency in High Speed mode is 50 MHz. On i.MX25, this change makes it possible to get 48 MHz from the USB PLL (240 MHz / 5 / 1) instead of only 40 MHz from the USB PLL (240 MHz / 3 / 2) or 33.25 MHz from the AHB clock (133 MHz / 2 / 2). Signed-off-by: Benoît Thébaudeau Reviewed-by: Fabio Estevam --- drivers/mmc/fsl_esdhc.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c index f3c63585a8..ca72627571 100644 --- a/drivers/mmc/fsl_esdhc.c +++ b/drivers/mmc/fsl_esdhc.c @@ -521,7 +521,13 @@ out: static void set_sysctl(struct mmc *mmc, uint clock) { - int div, pre_div; + int div = 1; +#ifdef ARCH_MXC + int pre_div = 1; +#else + int pre_div = 2; +#endif + int ddr_pre_div = mmc->ddr_mode ? 2 : 1; struct fsl_esdhc_priv *priv = mmc->priv; struct fsl_esdhc *regs = priv->esdhc_regs; int sdhc_clk = priv->sdhc_clk; @@ -530,18 +536,13 @@ static void set_sysctl(struct mmc *mmc, uint clock) if (clock < mmc->cfg->f_min) clock = mmc->cfg->f_min; - if (sdhc_clk / 16 > clock) { - for (pre_div = 2; pre_div < 256; pre_div *= 2) - if ((sdhc_clk / pre_div) <= (clock * 16)) - break; - } else - pre_div = 2; + while (sdhc_clk / (16 * pre_div * ddr_pre_div) > clock && pre_div < 256) + pre_div *= 2; - for (div = 1; div <= 16; div++) - if ((sdhc_clk / (div * pre_div)) <= clock) - break; + while (sdhc_clk / (div * pre_div * ddr_pre_div) > clock && div < 16) + div++; - pre_div >>= mmc->ddr_mode ? 2 : 1; + pre_div >>= 1; div -= 1; clk = (pre_div << 8) | (div << 4); -- 2.25.1