linux-kernel - [PATCH] usb: dwc2: gadget: remove D+ pull-up while no vbus with usb-role-switch

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Message-ID: <20220622160717.314580-1-fabrice.gasnier@foss.st.com>
Date:   Wed, 22 Jun 2022 18:07:17 +0200
From:   Fabrice Gasnier <fabrice.gasnier@...s.st.com>
To:     <hminas@...opsys.com>, <gregkh@...uxfoundation.org>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <amelie.delaunay@...s.st.com>, <alexandre.torgue@...s.st.com>,
        <fabrice.gasnier@...s.st.com>
Subject: [PATCH] usb: dwc2: gadget: remove D+ pull-up while no vbus with usb-role-switch

From: Amelie Delaunay <amelie.delaunay@...s.st.com>

When using usb-role-switch, D+ pull-up is set as soon as DTCL_SFTDISCON is
cleared, whatever the vbus valid signal state is. The pull-up should not
be set when vbus isn't present (this is determined by the drd controller).

This patch ensures that B-Session (so Peripheral role + vbus valid signal)
is valid before clearing the DCTL_SFTDISCON bit when role switch is used.
Keep original behavior when usb-role-switch isn't used.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
---
 drivers/usb/dwc2/gadget.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index fe2a58c758610..8b15742d9e8aa 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -3594,7 +3594,8 @@ void dwc2_hsotg_core_disconnect(struct dwc2_hsotg *hsotg)
 void dwc2_hsotg_core_connect(struct dwc2_hsotg *hsotg)
 {
 	/* remove the soft-disconnect and let's go */
-	dwc2_clear_bit(hsotg, DCTL, DCTL_SFTDISCON);
+	if (!hsotg->role_sw || (dwc2_readl(hsotg, GOTGCTL) & GOTGCTL_BSESVLD))
+		dwc2_clear_bit(hsotg, DCTL, DCTL_SFTDISCON);
 }
 
 /**
-- 
2.25.1