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

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Message-Id: <20190116101051.21202-1-paul.kocialkowski@bootlin.com>
Date:   Wed, 16 Jan 2019 11:10:51 +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] 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 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 and 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>
---
 drivers/usb/chipidea/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
index 7bfcbb23c2a4..11d3ee1e3fe5 100644
--- a/drivers/usb/chipidea/core.c
+++ b/drivers/usb/chipidea/core.c
@@ -954,8 +954,14 @@ 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->phy) && IS_ERR(ci->usb_phy))
+			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