[PATCH 2/2] ath79: add support for Dell SonicPoint ACi APL27-0B1

[Sander Vanheule]

Hi Tomasz,

On Sun, 2025-02-02 at 21:25 +0100, tomek at terefe.re wrote:
> W dniu 2.02.2025 o 19:37, Sander Vanheule pisze:
> > Hi Tomasz,
> 
> Hi
> 
> > 
> > On Sun, 2025-02-02 at 16:10 +0100, Tomasz Maciej Nowak wrote:
> > > +	reg_usb_vbus: regulator-usb-vbus {
> > > +		compatible = "regulator-fixed";
> > > +		regulator-name = "usb-vbus";
> > > +		regulator-min-microvolt = <5000000>;
> > > +		regulator-max-microvolt = <5000000>;
> > > +		gpios = <&gpio 4 GPIO_ACTIVE_LOW>;
> > > +	};
> > > +
> > > +	output-usb-vbus {
> > > +		compatible = "regulator-output";
> > > +		vout-supply = <&reg_usb_vbus>;
> > > +	};
> > > +};
> > > 
> > > +  DEVICE_PACKAGES += kmod-regulator-userspace-consumer
> > 
> > You could also add the regulator-boot-on to regulator-usb-vbus. If it is already enabled by the
> > bootloader, regulator-boot-on will keep it enabled. Otherwise it should cause the regulator to
> > be
> > enabled (GPIO set low in this case) when the driver probes.
> 
> Issue is, bootloader doesn't enable power on the USB port, it's done when the
> vendor modified EHCI driver was loaded, and while regulator-boot-on enables
> power, the regulator is turned off later, as no driver seem to use it (a bug in
> userspace-consumer driver?). I'll check if specifying hog property will allow to
> still toggle it from userspace.

While regulator-always-on act as a consumer, regulator-boot-on doesn't. I can imagine loading the
userspace-consumer driver has the side-effect of checking the consumer count and disabling on zero.

I expect a gpio-hog would conflict with the fixed-regulator in claiming the GPIO. And hogs don't
allow you to toggle them.

> 
> > You could also add regulator-always-on to regulator-usb-vbus, in which case the USB port can't
> > be
> > powered down anymore (from userspace). Is there any specific reason you would want to power the
> > port
> > down?
> 
> I can imagine someone using a LTE dongle to manage that AP, which sometime could
> lock itself up and only power-cycle could restore it. Power-cycling the USB port
> will restore the management capability without interrupting WiFi operation.

Sounds like a reasonable use-case.

Best,
Sander