From patchwork Mon Jan  8 13:01:10 2018

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Subject: phy: work around 'phys' references to usb-phy devices

From: Arnd Bergmann <arnd@arndb.de>

X-Patchwork-Id: 10149439

Message-Id: <20180108130116.80148-1-arnd@arndb.de>

To: Kishon Vijay Abraham I <kishon@ti.com>

Cc: Stefan Wahren <stefan.wahren@i2se.com>, devicetree@vger.kernel.org,

 Florian Fainelli <f.fainelli@gmail.com>, Arnd Bergmann <arnd@arndb.de>,

 Felipe Balbi <balbi@kernel.org>, linux-usb@vger.kernel.org,

 linux-kernel@vger.kernel.org, stable@vger.kernel.org,

 Eric Anholt <eric@anholt.net>, Rob Herring <robh+dt@kernel.org>,

 Andrzej Pietrasiewicz <andrzej.p@samsung.com>,

 linux-arm-kernel@lists.infradead.org

Date: Mon,  8 Jan 2018 14:01:10 +0100

Stefan Wahren reports a problem with a warning fix that was merged

for v4.15: we had lots of device nodes with a 'phys' property pointing

to a device node that is not compliant with the binding documented in

Documentation/devicetree/bindings/phy/phy-bindings.txt

This generally works because USB HCD drivers that support both the generic

phy subsystem and the older usb-phy subsystem ignore most errors from

phy_get() and related calls and then use the usb-phy driver instead.

However, usb_add_hcd() (along with the respective functions in dwc2 and

dwc3) propagate the EPROBE_DEFER return code so we can try again whenever

the driver gets loaded. In case the driver is written for the usb-phy

subsystem (like usb-generic-phy aka usb-nop-xceiv), we will never load

a generic-phy driver for it, and keep failing here.

There is only a small number of remaining usb-phy drivers that support

device tree, so this adds a workaround by providing a full list of the

potentially affected drivers, and always failing the probe with -ENODEV

here, which is the same behavior that we used to get with incorrect

device tree files. Since we generally want older kernels to also want

to work with the fixed devicetree files, it would be good to backport

the patch into stable kernels as well (3.13+ are possibly affected).

Reverting back to the DTS sources that work would in theory fix USB

support for now, but in the long run we'd run into the same problem

again when the drivers get ported from usb-phy to generic-phy.

Fixes: 014d6da6cb25 ("ARM: dts: bcm283x: Fix DTC warnings about missing phy-cells")

Link: https://marc.info/?l=linux-usb&m=151518314314753&w=2

Cc: stable@vger.kernel.org

Cc: Stefan Wahren <stefan.wahren@i2se.com>

Cc: Felipe Balbi <balbi@kernel.org>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---

This obviously needs to be tested, I wrote this up as a reply to

Stefan's bug report. I'm fairly sure that I covered all usb-phy

driver strings here. My goal is to have a fix merged into 4.15

rather than reverting all the DT fixes.

---

 drivers/phy/phy-core.c | 27 +++++++++++++++++++++++++++

 1 file changed, 27 insertions(+)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c

index b4964b067aec..bb4dd2a2de2d 100644

--- a/drivers/phy/phy-core.c

+++ b/drivers/phy/phy-core.c

@@ -387,6 +387,24 @@ int phy_calibrate(struct phy *phy)

 }

 EXPORT_SYMBOL_GPL(phy_calibrate);

+static struct of_device_id __maybe_unused legacy_usbphy[] = {

+	{ .compatible = "fsl,imx23-usbphy" },

+	{ .compatible = "fsl,imx6q-usbphy" },

+	{ .compatible = "fsl,imx6sl-usbphy" },

+	{ .compatible = "fsl,imx6sx-usbphy" },

+	{ .compatible = "fsl,imx6ul-usbphy" },

+	{ .compatible = "fsl,vf610-usbphy" },

+	{ .compatible = "nvidia,tegra20-usb-phy" },

+	{ .compatible = "nvidia,tegra30-usb-phy" },

+	{ .compatible = "nxp,isp1301" },

+	{ .compatible = "ti,am335x-usb-ctrl-module" },

+	{ .compatible = "ti,am335x-usb-phy" },

+	{ .compatible = "ti,keystone-usbphy" },

+	{ .compatible = "ti,twl6030-usb" },

+	{ .compatible = "usb-nop-xceiv" },

+	{},

+};

+

 /**

  * _of_phy_get() - lookup and obtain a reference to a phy by phandle

  * @np: device_node for which to get the phy

@@ -410,6 +428,15 @@ static struct phy *_of_phy_get(struct device_node *np, int index)

 	if (ret)

 		return ERR_PTR(-ENODEV);

+	/*

+	 * Some USB host controllers use a "phys" property to refer to

+	 * a device that does not have a generic phy driver but that

+	 * has a driver for the older usb-phy framework.

+	 * We must not return -EPROBE_DEFER for those, so bail out early.

+	 */

+	if (of_match_node(legacy_usbphy, args.np))

+		return ERR_PTR(-ENODEV);

+

 	mutex_lock(&phy_provider_mutex);

 	phy_provider = of_phy_provider_lookup(args.np);

 	if (IS_ERR(phy_provider) || !try_module_get(phy_provider->owner)) {