[PATCH v2] mmc: meson-mx-sdhc: Fix initialization frozen issue

[Ziyang Huang]

Commit 4bc31edebde5 ("mmc: core: Set HS clock speed before sending
HS CMD13") set HS clock (52MHz) before switching to HS mode. For this
freq, FCLK_DIV5 will be selected and div value is 10 (reg value is 9).
Then we set rx_clk_phase to 11 or 15 which is out of range and make
hardware frozen. After we send command request, no irq will be
interrupted and the mmc driver will keep to wait for request finished,
even durning rebooting.

So let's set it to Phase 90 which should work in most cases. Then let
meson_mx_sdhc_execute_tuning() to find the accurate value for data
transfer.

If this doesn't work, maybe need to define a factor in dts.

Fixes: e4bf1b0970ef ("mmc: host: meson-mx-sdhc: new driver for the Amlogic Meson SDHC host")
Signed-off-by: Ziyang Huang <hzyitc at outlook.com>
---
Changes since v1:
  Use Phase 90 instand of value 1

 drivers/mmc/host/meson-mx-sdhc-mmc.c | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/drivers/mmc/host/meson-mx-sdhc-mmc.c b/drivers/mmc/host/meson-mx-sdhc-mmc.c
index 97168cdfa8e9..29698fceb89c 100644
--- a/drivers/mmc/host/meson-mx-sdhc-mmc.c
+++ b/drivers/mmc/host/meson-mx-sdhc-mmc.c
@@ -269,7 +269,7 @@ static int meson_mx_sdhc_enable_clks(struct mmc_host *mmc)
 static int meson_mx_sdhc_set_clk(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct meson_mx_sdhc_host *host = mmc_priv(mmc);
-	u32 rx_clk_phase;
+	u32 val, rx_clk_phase;
 	int ret;
 
 	meson_mx_sdhc_disable_clks(mmc);
@@ -290,27 +290,11 @@ static int meson_mx_sdhc_set_clk(struct mmc_host *mmc, struct mmc_ios *ios)
 		mmc->actual_clock = clk_get_rate(host->sd_clk);
 
 		/*
-		 * according to Amlogic the following latching points are
-		 * selected with empirical values, there is no (known) formula
-		 * to calculate these.
+		 * Phase 90 should work in most cases. For data transmission,
+		 * meson_mx_sdhc_execute_tuning() will find a accurate value
 		 */
-		if (mmc->actual_clock > 100000000) {
-			rx_clk_phase = 1;
-		} else if (mmc->actual_clock > 45000000) {
-			if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330)
-				rx_clk_phase = 15;
-			else
-				rx_clk_phase = 11;
-		} else if (mmc->actual_clock >= 25000000) {
-			rx_clk_phase = 15;
-		} else if (mmc->actual_clock > 5000000) {
-			rx_clk_phase = 23;
-		} else if (mmc->actual_clock > 1000000) {
-			rx_clk_phase = 55;
-		} else {
-			rx_clk_phase = 1061;
-		}
-
+		regmap_read(host->regmap, MESON_SDHC_CLKC, &val);
+		rx_clk_phase = FIELD_GET(MESON_SDHC_CLKC_CLK_DIV, val) / 4;
 		regmap_update_bits(host->regmap, MESON_SDHC_CLK2,
 				   MESON_SDHC_CLK2_RX_CLK_PHASE,
 				   FIELD_PREP(MESON_SDHC_CLK2_RX_CLK_PHASE,
-- 
2.34.1