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SubjectRe: [RFC PATCH] ARM: dts: imx6qdl: specify vcc-supply for NOP USB PHYs
On Fri, Nov 13, 2020 at 04:28:55PM +0100, Ahmad Fatoum wrote:
> The SoC dtsi lists a NOP USB PHY for each of the two HSIC-only USB
> controllers. Their device tree node doesn't indicate a vcc-supply
> resulting in:
>
> usb_phy_generic usbphynop1: supply vcc not found, using dummy regulator
> usb_phy_generic usbphynop2: supply vcc not found, using dummy regulator

So the patch is all for removing this kernel message, with introducing
the following potential breakage?

Shawn

>
> warnings on boot up. The USB IP vcc-supply - separate from the vusb - is
> hardwired to LDO_2P5[1], which we already have a device tree node for.
> Reference it for the dummy "phy" as well.
>
> This will lead to breakage (probe deferment) for kernels that:
> - Use a HSIC USB controller
> - Use this new device tree
> - but have CONFIG_REGULATOR_ANATOP disabled
>
> Because while the regulator is always-on, it can't be resolved when
> there is no driver for it.
>
> As there are
>
> - no affected upstream device trees
> - existing device trees are unaffected without recompilation
> - disabling CONFIG_REGULATOR_ANATOP is explicitly a non-recommended
> configuration per symbol help text
>
> this potential breakage is deemed acceptable.
>
> [1]: i.MX 6Dual/6Quad Reference Manual, Rev. C,
> Figure 53-1. Power System Overview
>
> Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> arch/arm/boot/dts/imx6qdl.dtsi | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
> index 43edbf1156c7..22e4c142de13 100644
> --- a/arch/arm/boot/dts/imx6qdl.dtsi
> +++ b/arch/arm/boot/dts/imx6qdl.dtsi
> @@ -131,11 +131,13 @@ pmu: pmu {
>
> usbphynop1: usbphynop1 {
> compatible = "usb-nop-xceiv";
> + vcc-supply = <&reg_vdd2p5>;
> #phy-cells = <0>;
> };
>
> usbphynop2: usbphynop2 {
> compatible = "usb-nop-xceiv";
> + vcc-supply = <&reg_vdd2p5>;
> #phy-cells = <0>;
> };
>
> --
> 2.28.0
>

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