linux-kernel - [PATCH 12/14] mmc: meson-gx: fix dual data rate mode frequencies

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Date:   Fri,  4 Aug 2017 19:43:51 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>
Cc:     Jerome Brunet <jbrunet@...libre.com>, linux-mmc@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 12/14] mmc: meson-gx: fix dual data rate mode frequencies

In DDR modes, meson mmc controller requires an input rate twice as fast
as the output rate

Fixes: 51c5d8447bd7 ("MMC: meson: initial support for GX platforms")
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---
 drivers/mmc/host/meson-gx-mmc.c | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 560de8faea50..f973278a3f8d 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -298,14 +298,29 @@ static void meson_mmc_clk_phase_dflt(struct meson_host *host)
 	writel(val, host->regs + SD_EMMC_CLOCK);
 }
 
-static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
+static bool meson_mmc_timing_is_ddr(struct mmc_ios *ios)
+{
+	if (ios->timing == MMC_TIMING_MMC_DDR52 ||
+	    ios->timing == MMC_TIMING_UHS_DDR50 ||
+	    ios->timing == MMC_TIMING_MMC_HS400)
+		return true;
+
+	return false;
+}
+
+static int meson_mmc_clk_set(struct meson_host *host, struct mmc_ios *ios)
 {
 	struct mmc_host *mmc = host->mmc;
+	unsigned long rate = ios->clock;
 	int ret;
 	u32 cfg;
 
+	/* DDR modes require higher module clock */
+	if (meson_mmc_timing_is_ddr(ios))
+		rate <<= 1;
+
 	/* Same request - bail-out */
-	if (host->req_rate == clk_rate)
+	if (host->req_rate == rate)
 		return 0;
 
 	/* stop clock */
@@ -314,25 +329,29 @@ static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
 	writel(cfg, host->regs + SD_EMMC_CFG);
 	host->req_rate = 0;
 
-	if (!clk_rate) {
+	if (!rate) {
 		mmc->actual_clock = 0;
 		/* return with clock being stopped */
 		return 0;
 	}
 
-	ret = clk_set_rate(host->signal_clk, clk_rate);
+	ret = clk_set_rate(host->signal_clk, rate);
 	if (ret) {
 		dev_err(host->dev, "Unable to set cfg_div_clk to %lu. ret=%d\n",
-			clk_rate, ret);
+			rate, ret);
 		return ret;
 	}
 
-	host->req_rate = clk_rate;
+	host->req_rate = rate;
 	mmc->actual_clock = clk_get_rate(host->signal_clk);
 
+	/* We should report the real output frequency of the controller */
+	if (meson_mmc_timing_is_ddr(ios))
+		mmc->actual_clock >>= 1;
+
 	dev_dbg(host->dev, "clk rate: %u Hz\n", mmc->actual_clock);
-	if (clk_rate != mmc->actual_clock)
-		dev_dbg(host->dev, "requested rate was %lu\n", clk_rate);
+	if (ios->clock != mmc->actual_clock)
+		dev_dbg(host->dev, "requested rate was %u\n", ios->clock);
 
 	/* (re)start clock */
 	cfg = readl(host->regs + SD_EMMC_CFG);
@@ -499,16 +518,14 @@ static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	val |= FIELD_PREP(CFG_BUS_WIDTH_MASK, bus_width);
 
 	val &= ~CFG_DDR;
-	if (ios->timing == MMC_TIMING_UHS_DDR50 ||
-	    ios->timing == MMC_TIMING_MMC_DDR52 ||
-	    ios->timing == MMC_TIMING_MMC_HS400)
+	if (meson_mmc_timing_is_ddr(ios))
 		val |= CFG_DDR;
 
 	val &= ~CFG_CHK_DS;
 	if (ios->timing == MMC_TIMING_MMC_HS400)
 		val |= CFG_CHK_DS;
 
-	err = meson_mmc_clk_set(host, ios->clock);
+	err = meson_mmc_clk_set(host, ios);
 	if (err)
 		dev_err(host->dev, "Failed to set clock: %d\n,", err);
 
-- 
2.9.4