From: Louis Chauvet louis.chauvet@bootlin.com
When the OTG USB port is used to power the SoC, configured as peripheral and used in gadget mode, there is a disconnection about 6 seconds after the gadget is configured and enumerated.
The problem was observed on a Radxa Rock Pi S board, which can only be powered by the only USB-C connector. That connector is the only one usable in gadget mode. This implies the USB cable is connected from before boot and never disconnects while the kernel runs.
The problem happens because of the PHY driver code flow, summarized as:
* UDC start code (triggered via configfs at any time after boot) -> phy_init -> rockchip_usb2phy_init -> schedule_delayed_work(otg_sm_work [A], 6 sec) -> phy_power_on -> rockchip_usb2phy_power_on -> enable clock -> rockchip_usb2phy_reset
* Now the gadget interface is up and running.
* 6 seconds later otg_sm_work starts [A] -> rockchip_usb2phy_otg_sm_work(): if (B_IDLE state && VBUS present && ...): schedule_delayed_work(&rport->chg_work [B], 0);
* immediately the chg_detect_work starts [B] -> rockchip_chg_detect_work(): if chg_state is UNDEFINED: if (!rport->suspended): rockchip_usb2phy_power_off() <--- [X]
At [X], the PHY is powered off, causing a disconnection. This quickly triggers a new connection and following re-enumeration, but any connection that had been established during the 6 seconds is broken.
The code already checks for !rport->suspended (which, somewhat counter-intuitively, means the PHY is powered on), so add a guard for VBUS as well to avoid a disconnection when a cable is connected.
Fixes: 98898f3bc83c ("phy: rockchip-inno-usb2: support otg-port for rk3399") Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/lkml/20250414185458.7767aabc@booty/ Signed-off-by: Louis Chauvet louis.chauvet@bootlin.com Co-developed-by: Luca Ceresoli luca.ceresoli@bootlin.com Signed-off-by: Luca Ceresoli luca.ceresoli@bootlin.com Reviewed-by: Théo Lebrun theo.lebrun@bootlin.com --- drivers/phy/rockchip/phy-rockchip-inno-usb2.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c index b0f23690ec30..0106d7b7ae24 100644 --- a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c +++ b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c @@ -821,14 +821,16 @@ static void rockchip_chg_detect_work(struct work_struct *work) container_of(work, struct rockchip_usb2phy_port, chg_work.work); struct rockchip_usb2phy *rphy = dev_get_drvdata(rport->phy->dev.parent); struct regmap *base = get_reg_base(rphy); - bool is_dcd, tmout, vout; + bool is_dcd, tmout, vout, vbus_attach; unsigned long delay;
+ vbus_attach = property_enabled(rphy->grf, &rport->port_cfg->utmi_bvalid); + dev_dbg(&rport->phy->dev, "chg detection work state = %d\n", rphy->chg_state); switch (rphy->chg_state) { case USB_CHG_STATE_UNDEFINED: - if (!rport->suspended) + if (!rport->suspended && !vbus_attach) rockchip_usb2phy_power_off(rport->phy); /* put the controller in non-driving mode */ property_enable(base, &rphy->phy_cfg->chg_det.opmode, false);