linux-kernel - [PATCH 3/3] usb: dwc2: Power off the phy on shutdown

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Date:   Wed,  5 Apr 2017 16:06:12 +0200
From:   Sjoerd Simons <sjoerd.simons@...labora.co.uk>
To:     John Youn <johnyoun@...opsys.com>, Heiko Stuebner <heiko@...ech.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] usb: dwc2: Power off the phy on shutdown

On a board with a usb->sata bridge behind a usb hub, the bridge only
appears on cold boot and becomes non-functional after a reboot. Testing
thusfar shows that it gets confused during reboot if the usb hub is left
on (Interestingly a similar setup without the usb hub in between doesn't
have the issue).  This can be avoided by turning off the phy (thus vbus)
during shutdown, which turns off the usb hub.

For devices where this isn't required, powering down the phy is harmless
so we can do this unconditionally.

Signed-off-by: Sjoerd Simons <sjoerd.simons@...labora.co.uk>

---

 drivers/usb/dwc2/platform.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 9564bc76c56f..b5bbc433c94d 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -348,6 +348,9 @@ static void dwc2_driver_shutdown(struct platform_device *dev)
 {
 	struct dwc2_hsotg *hsotg = platform_get_drvdata(dev);

+	if (hsotg->phy)
+		phy_power_off(hsotg->phy);
+
 	disable_irq(hsotg->irq);
 }

-- 
2.11.0