[PATCH 1/2] mmc: renesas-sdhi: Always configure default SDnH clock rate to 800 MHz

Marek Vasut marek.vasut+renesas at mailbox.org
Mon Feb 27 23:49:27 CET 2023

The prior stage bootloader might have left the SDnCKCR register in completely
arbitrary state before passing control to U-Boot, which includes the register
being populated with incorrect values. Currently the SDHI driver will attempt
to use clock framework to configure SDn clock, which may fail in case SDnCKCR
contains invalid values for the SDnH clock, because the clock framework would
not be able to determine SDnH clock rate and would get -EINVAL instead, which
in turn would not allow the clock framework to determine the correct SDn clock
divider ratio.

This failure occurs specifically in case SDnCKCR reads back 0x209 .

Correct the problem by first setting default SDnH clock rate to 800 MHz, thus
assuring the SDnCKCR SDnH bits are correct, and only afterward set up the SDn
clock rate to default 200 MHz.

Note that the SDHI driver may reconfigure SDnH clock later based on IOS
settings obtained from the attached card, the 800 MHz set up here is only
the default value.

Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
Cc: Jaehoon Chung <jh80.chung at samsung.com>
Cc: Peng Fan <peng.fan at nxp.com>
 drivers/mmc/renesas-sdhi.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/renesas-sdhi.c b/drivers/mmc/renesas-sdhi.c
index 4a1accebfcb..2473261f3c4 100644
--- a/drivers/mmc/renesas-sdhi.c
+++ b/drivers/mmc/renesas-sdhi.c
@@ -977,8 +977,16 @@ static int renesas_sdhi_probe(struct udevice *dev)
 	/* optional SDnH clock */
 	ret = clk_get_by_name(dev, "clkh", &priv->clkh);
-	if (ret < 0)
+	if (ret < 0) {
 		dev_dbg(dev, "failed to get clkh\n");
+	} else {
+		ret = clk_set_rate(&priv->clkh, 800000000);
+		if (ret < 0) {
+			dev_err(dev, "failed to set rate for SDnH clock\n");
+			clk_free(&priv->clk);
+			return ret;
+		}
+	}
 	/* set to max rate */
 	ret = clk_set_rate(&priv->clk, 200000000);

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