Hello Peter,
On 05/22/2015 12:30 PM, Peter Seiderer wrote:
> Hello Philipp,
>
>> Gesendet: Freitag, 22. Mai 2015 um 13:05 Uhr
>> Von: "Philipp Zabel" <p.zabel@xxxxxxxxxxxxxx>
>> Am Donnerstag, den 21.05.2015, 19:45 +0200 schrieb Peter Seiderer:
>>>
>>> <snip>
>>>
>>> +
>>> + reg_can_xcvr: regulator@3 {
>>> + compatible = "regulator-fixed";
>>> + reg = <3>;
>>> + regulator-name = "CAN XCVR";
>>> + regulator-min-microvolt = <3300000>;
>>> + regulator-max-microvolt = <3300000>;
>>> + pinctrl-names = "default";
>>> + pinctrl-0 = <&pinctrl_can_xcvr>;
>>> + gpio = <&gpio1 2 GPIO_ACTIVE_HIGH>;
>>
>> According to
>> Documentation/devicetree/bindings/regulator/fixed-regulator.txt
>> this should have:
>> enable-active-high;
>>
>> instead of the gpio phandle flag (which is ignored). Otherwise an active
>> low GPIO is assumed.
>>
>
> Thanks for review...
>
> I was a bit confused from the original:
>
> imx6qdl-tx6.dtsi:103: reg_can_xcvr: regulator@3 {
> imx6qdl-tx6.dtsi-104- compatible = "regulator-fixed";
> imx6qdl-tx6.dtsi-105- reg = <3>;
> imx6qdl-tx6.dtsi-106- regulator-name = "CAN XCVR";
> imx6qdl-tx6.dtsi-107- regulator-min-microvolt = <3300000>;
> imx6qdl-tx6.dtsi-108- regulator-max-microvolt = <3300000>;
> imx6qdl-tx6.dtsi-109- pinctrl-names = "default";
> imx6qdl-tx6.dtsi:110: pinctrl-0 = <&pinctrl_flexcan_xcvr>;
> imx6qdl-tx6.dtsi-111- gpio = <&gpio4 21 GPIO_ACTIVE_HIGH>;
> imx6qdl-tx6.dtsi-112- enable-active-low;
> imx6qdl-tx6.dtsi-113- };
>
> ...and removed the default 'enable-active-low'...
>
> Maybe GPIO_ACTIVE_LOW is the right thing?
>
No. The flags aren't read from the device tree and enable-active-low
is the default.
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/drivers/regulator/fixed.c#n81
> From the other files:
>
So if this board really wants an "active high" enable pin, it's likely
not operating properly:
> imx28-tx28.dts:90: reg_can_xcvr: regulator@4 {
> imx28-tx28.dts-91- compatible = "regulator-fixed";
> imx28-tx28.dts-92- reg = <4>;
> imx28-tx28.dts-93- regulator-name = "CAN XCVR";
> imx28-tx28.dts-94- regulator-min-microvolt = <3300000>;
> imx28-tx28.dts-95- regulator-max-microvolt = <3300000>;
> imx28-tx28.dts-96- gpio = <&gpio1 0 GPIO_ACTIVE_HIGH>;
> imx28-tx28.dts-97- pinctrl-names = "default";
> imx28-tx28.dts:98: pinctrl-0 = <&tx28_flexcan_xcvr_pins>;
> imx28-tx28.dts-99- };
>
> <snip>
>
> Any further advice from your side which solution is the right one?
>
> - GPIO_ACTIVE_HIGH/enable-active-high
> - GPIO_ACTIVE_LOW
>
The pad is active low on the TJA1040 transceiver on the Nitrogen6x,
so you don't want "enable-active-high" and could be more explicit with
GPIO_ACTIVE_LOW in the gpio reference, but it won't be parsed or
acted upon.
i.e.
reg_can_xcvr: regulator@3 {
compatible = "regulator-fixed";
reg = <3>;
regulator-name = "CAN XCVR";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_can_xcvr>;
gpio = <&gpio1 2 0>;
}
Regards,
Eric
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