Re: [PATCHv3 2/2] ARM: dts: broadcom: model USB VBUS power with regulator-fixed

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] usb: bcma: unclaimed vbus-supply regulator disables USB power after 30s
- [Medium] usb: bcma: silent power management failure due to missing vcc GPIO
--

commit 5639b159d14f6b05d776251fb2e51af77ccdaf1b
Author: Rosen Penev <rosenp@gmail.com>
Subject: ARM: dts: broadcom: model USB VBUS power with regulator-fixed

This commit replaces the undocumented vcc-gpio property on usb2/usb3
controller nodes with the standard vbus-supply and regulator-fixed model. 
Boards now declare a regulator bound to the chipcommon GPIO, preserving 
polarity and using regulator-boot-on to mirror the CFE state.

> diff --git a/arch/arm/boot/dts/broadcom/bcm4708-buffalo-wxr-1750dhp.dts b/arch/arm/boot/dts/broadcom/bcm4708-buffalo-wxr-1750dhp.dts
> index f5c95c9a712ec..80414c72f9129 100644
> --- a/arch/arm/boot/dts/broadcom/bcm4708-buffalo-wxr-1750dhp.dts
> +++ b/arch/arm/boot/dts/broadcom/bcm4708-buffalo-wxr-1750dhp.dts
> @@ -101,6 +101,16 @@ led-usb {
>  			trigger-sources = <&xhci_port1 &ehci_port1 &ohci_port1>;
>  		};
>  	};
> +
> +	usb_power: regulator-usb {
> +		compatible = "regulator-fixed";
> +		regulator-name = "usb-vcc";
> +		regulator-min-microvolt = <5000000>;
> +		regulator-max-microvolt = <5000000>;
> +		regulator-boot-on;
> +		gpios = <&chipcommon 10 GPIO_ACTIVE_HIGH>;

[Severity: High]
Does this regulator definition need regulator-always-on? 

The bcma-hcd driver in drivers/usb/host/bcma-hcd.c:bcma_hcd_probe() attempts
to fetch a raw "vcc" GPIO rather than claiming this vbus-supply regulator. As
a result, the new regulator remains unclaimed with a zero use count, and the
regulator core will automatically disable USB power 30 seconds after boot when
it disables unclaimed non-always-on regulators.

> +		enable-active-high;
> +	};
>  };
>  
>  &srab {
> @@ -130,7 +140,7 @@ port@4 {
>  };
>  
>  &usb3 {
> -	vcc-gpio = <&chipcommon 10 GPIO_ACTIVE_HIGH>;
> +	vbus-supply = <&usb_power>;

[Severity: Medium]
Will replacing the vcc-gpio property with vbus-supply break power management
for this device?

When bcma_hcd_probe() fails to fetch the vcc GPIO descriptor, the usb_dev
gpio_desc remains NULL. Later power management calls, such as during suspend
in bcma_hcd_suspend() which calls bcma_hci_platform_power_gpio(), will simply
return early upon seeing a NULL descriptor. This silently skips all hardware
power control operations on state transitions.

>  };
>  
>  &usb3_phy {

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260924233831.127617-3-rosenp@gmail.com?part=1