linux-kernel - [PATCH v3 7/7] usb: musb: jz4740: Disable pullup at init

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Date:   Tue, 10 Dec 2019 18:11:10 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Bin Liu <b-liu@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     od@...c.me, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH v3 7/7] usb: musb: jz4740: Disable pullup at init

The pullup may be already enabled before the driver is initialized.
It has to be disabled at init time, as we cannot guarantee that a gadget
driver will be bound to the UDC.

Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---

Notes:
    v3: New patch

 drivers/usb/musb/jz4740.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/musb/jz4740.c b/drivers/usb/musb/jz4740.c
index f948eca654f3..1af9e4053312 100644
--- a/drivers/usb/musb/jz4740.c
+++ b/drivers/usb/musb/jz4740.c
@@ -75,6 +75,7 @@ static const struct musb_hdrc_config jz4740_musb_config = {
 static int jz4740_musb_init(struct musb *musb)
 {
 	struct device *dev = musb->controller->parent;
+	u8 power;
 	int err;
 
 	if (dev->of_node)
@@ -97,6 +98,14 @@ static int jz4740_musb_init(struct musb *musb)
 	musb->isr = jz4740_musb_interrupt;
 	musb->dma_share_usb_irq = true;
 
+	/*
+	 * If the SoC booted from USB the pullup might still be set.
+	 * Disable it until a gadget is bound.
+	 */
+	power = musb_readb(musb->mregs, MUSB_POWER);
+	power &= ~MUSB_POWER_SOFTCONN;
+	musb_writeb(musb->mregs, MUSB_POWER, power);
+
 	return 0;
 }
 
-- 
2.24.0