linux-kernel - [PATCH] phy: renesas: rcar-gen3-usb2: Disable clearing VBUS in over-current

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Message-Id: <1565081479-24340-1-git-send-email-yoshihiro.shimoda.uh@renesas.com>
Date:   Tue,  6 Aug 2019 17:51:19 +0900
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     kishon@...com
Cc:     linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        stable@...r.kernel.org,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Subject: [PATCH] phy: renesas: rcar-gen3-usb2: Disable clearing VBUS in over-current

The hardware manual should be revised, but the initial value of
VBCTRL.OCCLREN is set to 1 actually. If the bit is set, the hardware
clears VBCTRL.VBOUT and ADPCTRL.DRVVBUS registers automatically
when the hardware detects over-current signal from a USB power switch.
However, since the hardware doesn't have any registers which
indicates over-current, the driver cannot handle it at all. So, if
"is_otg_channel" hardware detects over-current, since ADPCTRL.DRVVBUS
register is cleared automatically, the channel cannot be used after
that.

To resolve this behavior, this patch sets the VBCTRL.OCCLREN to 0
to keep ADPCTRL.DRVVBUS even if the "is_otg_channel" hardware
detects over-current. (We assume a USB power switch itself protects
over-current and turns the VBUS off.)

This patch is inspired by a BSP patch from Kazuya Mizuguchi.

Fixes: 1114e2d31731 ("phy: rcar-gen3-usb2: change the mode to OTG on the combined channel")
Cc: <stable@...r.kernel.org> # v4.5+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
---
 This patch might be difficult to backport to v4.9 or older because
 the v4.13 added vendor specific directories by commit
 0b56e9a7e835 ("phy: Group vendor specific phy drivers").

 drivers/phy/renesas/phy-rcar-gen3-usb2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/phy/renesas/phy-rcar-gen3-usb2.c b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
index 8ffba67..b7f6b13 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -61,6 +61,7 @@
 					 USB2_OBINT_IDDIGCHG)

 /* VBCTRL */
+#define USB2_VBCTRL_OCCLREN		BIT(16)
 #define USB2_VBCTRL_DRVVBUSSEL		BIT(8)

 /* LINECTRL1 */
@@ -374,6 +375,7 @@ static void rcar_gen3_init_otg(struct rcar_gen3_chan *ch)
 	writel(val, usb2_base + USB2_LINECTRL1);

 	val = readl(usb2_base + USB2_VBCTRL);
+	val &= ~USB2_VBCTRL_OCCLREN;
 	writel(val | USB2_VBCTRL_DRVVBUSSEL, usb2_base + USB2_VBCTRL);
 	val = readl(usb2_base + USB2_ADPCTRL);
 	writel(val | USB2_ADPCTRL_IDPULLUP, usb2_base + USB2_ADPCTRL);
-- 
2.7.4