linux-kernel - [PATCH v3] usb: chipidea: Grab the (legacy) USB PHY by phandle first

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Message-Id: <20190215162225.19284-1-paul.kocialkowski@bootlin.com>
Date:   Fri, 15 Feb 2019 17:22:25 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Peter Chen <Peter.Chen@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: [PATCH v3] usb: chipidea: Grab the (legacy) USB PHY by phandle first

According to the chipidea driver bindings, the USB PHY is specified via
the "phys" phandle node. However, this only takes effect for USB PHYs
that use the common PHY framework. For legacy USB PHYs, a simple lookup
based on the USB PHY type is done instead.

This does not play out well when more than one USB PHY is registered,
since the first registered PHY matching the type will always be
returned regardless of what the driver was bound to.

Fix this by looking up the PHY based on the "phys" phandle node.
Although generic PHYs are rather matched by their "phys-name" and not
the "phys" phandle directly, there is no helper for similar lookup on
legacy PHYs and it's probably not worth the effort to add it.

When no legacy USB PHY is found by phandle, fallback to grabbing any
registered USB2 PHY. This ensures backward compatibility if some users
were actually relying on this mechanism.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
---
Changes since v2:
* Fixed typos in commit message.

Changes since v1:
* Only consider legacy USB PHY error for fallback as suggested;
* Checked against EPROBE_DEFER before entering fallback.

 drivers/usb/chipidea/core.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
index 7bfcbb23c2a4..016e4004fe9d 100644
--- a/drivers/usb/chipidea/core.c
+++ b/drivers/usb/chipidea/core.c
@@ -954,8 +954,15 @@ static int ci_hdrc_probe(struct platform_device *pdev)
 	} else if (ci->platdata->usb_phy) {
 		ci->usb_phy = ci->platdata->usb_phy;
 	} else {
+		ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys",
+							  0);
 		ci->phy = devm_phy_get(dev->parent, "usb-phy");
-		ci->usb_phy = devm_usb_get_phy(dev->parent, USB_PHY_TYPE_USB2);
+
+		/* Fallback to grabbing any registered USB2 PHY */
+		if (IS_ERR(ci->usb_phy) &&
+		    PTR_ERR(ci->usb_phy) != -EPROBE_DEFER)
+			ci->usb_phy = devm_usb_get_phy(dev->parent,
+						       USB_PHY_TYPE_USB2);

 		/* if both generic PHY and USB PHY layers aren't enabled */
 		if (PTR_ERR(ci->phy) == -ENOSYS &&
-- 
2.20.1