BUG 4.4rc-4: wrong eMMC signaling voltage reported

[Holger Schurig]

Hi,

I have an i.MX6Q based system that cannot provide 1.8V voltage towards
the eMMC. But Linux 4.4-rc4 reports 1.8V for the eMMC, but this is
impossible. Neither my hardware allows this, nor does the DT say it.

root@imx6q:/sys/kernel/debug# cat mmc1/ios
clock:          52000000 Hz
actual clock:   49500000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    8 (mmc DDR52)
signal voltage: 0 (1.80 V)
driver type:    0 (driver type B)

My device tree however tells that I don't have 1.8V:

/* this is the built in eMMC */
&usdhc4 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_usdhc4>;
        bus-width = <8>;
        non-removable;
        vmmc-supply = <&reg_3p3v>;
        max-frequency = <198000000>;
        no-1-8-v;
        status = "okay";
};




Fun fact: for the SDCARD things are correctly reported:

root@imx6q:/sys/kernel/debug# cat mmc1/ios
clock:          36000000 Hz
actual clock:   33000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      2 (4 bits)
timing spec:    2 (sd high-speed)
signal voltage: 0 (3.30 V)
driver type:    0 (driver type B)

And here my device tree excerpt:

/* this is the SDCARD slot */
&usdhc2 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_usdhc2>;
        cd-gpios = <&gpio1 2 GPIO_ACTIVE_LOW>;
        wp-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
        vmmc-supply = <&reg_3p3v>;
        max-frequency = <36000000>;
        no-1-8-v;
        status = "okay";
};
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