[PATCH v3] ARM: dts: imx: Set default tuning step for imx7d usdhc

[Xiaolei Wang]

If the tuning step is not set, the tuning step is set to 1.
For some sd cards, the following Tuning timeout will occur.

Tuning failed, falling back to fixed sampling clock
mmc0: Tuning failed, falling back to fixed sampling clock

So set the default tuning step. This refers to the NXP vendor's
commit below:

https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/
arch/arm/boot/dts/imx7s.dtsi#L1216-L1217

Fixes: 1e336aa0c025 ("mmc: sdhci-esdhc-imx: correct the tuning start tap and step setting")
Signed-off-by: Xiaolei Wang <xiaolei.wang at windriver.com>
Reviewed-by: Fabio Estevam <festevam at gmail.com>
---

v3:
  * Add the timeout message to commit log

v2:
  * Refer to https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm/boot/dts/imx7s.dtsi#L1216-L1217
    and add the following attributes for all usdhc of imx7:
      fsl,tuning-step = <2>;
      fsl,tuning-start-tap = <20>;

 arch/arm/boot/dts/nxp/imx/imx7s.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/nxp/imx/imx7s.dtsi b/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
index 54026c2c93fa..6ffb428dc939 100644
--- a/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
+++ b/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
@@ -1184,6 +1184,8 @@ usdhc1: mmc at 30b40000 {
 					<&clks IMX7D_USDHC1_ROOT_CLK>;
 				clock-names = "ipg", "ahb", "per";
 				bus-width = <4>;
+				fsl,tuning-step = <2>;
+				fsl,tuning-start-tap = <20>;
 				status = "disabled";
 			};
 
@@ -1196,6 +1198,8 @@ usdhc2: mmc at 30b50000 {
 					<&clks IMX7D_USDHC2_ROOT_CLK>;
 				clock-names = "ipg", "ahb", "per";
 				bus-width = <4>;
+				fsl,tuning-step = <2>;
+				fsl,tuning-start-tap = <20>;
 				status = "disabled";
 			};
 
@@ -1208,6 +1212,8 @@ usdhc3: mmc at 30b60000 {
 					<&clks IMX7D_USDHC3_ROOT_CLK>;
 				clock-names = "ipg", "ahb", "per";
 				bus-width = <4>;
+				fsl,tuning-step = <2>;
+				fsl,tuning-start-tap = <20>;
 				status = "disabled";
 			};
 
-- 
2.25.1