linux-kernel - [RFC PATCH] ARM: dts: imx6qdl: specify vcc-supply for NOP USB PHYs

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Message-Id: <20201113152856.3758-1-a.fatoum@pengutronix.de>
Date:   Fri, 13 Nov 2020 16:28:55 +0100
From:   Ahmad Fatoum <a.fatoum@...gutronix.de>
To:     Rob Herring <robh+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     Ahmad Fatoum <a.fatoum@...gutronix.de>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH] ARM: dts: imx6qdl: specify vcc-supply for NOP USB PHYs

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

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@...tron.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.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