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About changing "Selected Driver Strength" field of HS_TIMING [185] of eMMC device

Question asked by Yasushi Hasegawa on Apr 24, 2019
Latest reply on Apr 24, 2019 by igorpadykov

Dear Community members,

 

Our customer is mass producing using i.MX7Solo and Android's "IMX6_M6.0.1_2.1.0".
Customer is verifying that the eMMC device will be revised.

 

They refer to:
myandroid/kernel_imx/Documentation/devicetree/bindings/mmc/mmc.txt

From the above file they confirmed the following contents.
-----------------
Example with sdio function subnode:

mmc3: mmc@01c12000 {
#address-cells = <1>;
#size-cells = <0>;

pinctrl-names = "default";
pinctrl-0 = <&mmc3_pins_a>;
vmmc-supply = <&reg_vmmc3>;
bus-width = <4>;
-----------------


[Customer's Requirement]
The customer wants to change the [Selected Driver Strength] field of HS_TIMING [185] of the eMMC device.

 

[Question.1]
How can the customer fulfill the above requirement by writing it in the ".dts" file?

 

[Questino.2]
Take the following .dts file as an example.
Android/kernel_imx/arch/arm/boot/dts/imx7d-sdb.dts
-----
&usdhc3 {
pinctrl-names = "default", "state_100mhz", "state_200mhz";
pinctrl-0 = <&pinctrl_usdhc3>;
pinctrl-1 = <&pinctrl_usdhc3_100mhz>;
pinctrl-2 = <&pinctrl_usdhc3_200mhz>;
assigned-clocks = <&clks IMX7D_USDHC3_ROOT_CLK>;
assigned-clock-rates = <400000000>;
bus-width = <8>;
non-removable;
status = "okay";
};
-----
For example, where is the source code where "bus-width = <8>;" is executed?
Customer is also thinking about source code modification.

 

Best Regards,

Yasushi Hasegawa

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