linux-kernel - [PATCH 0/2] phy: rockchip: inno-usb2: fix gadget mode disconnection after 6 seconds

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Message-Id: <20250722-rk3308-fix-usb-gadget-phy-disconnect-v1-0-239872f05f17@bootlin.com>
Date: Tue, 22 Jul 2025 10:43:42 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Vinod Koul <vkoul@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Heiko Stuebner <heiko@...ech.de>, William Wu <wulf@...k-chips.com>
Cc: Kever Yang <kever.yang@...k-chips.com>, 
 Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>, 
 Alan Stern <stern@...land.harvard.edu>, 
 Louis Chauvet <louis.chauvet@...tlin.com>, 
 Hervé Codina <herve.codina@...tlin.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 linux-phy@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
 linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 0/2] phy: rockchip: inno-usb2: fix gadget mode
 disconnection after 6 seconds

The USB OTG port of the RK3308 exibits a bug when:

 - configured as peripheral, and
 - used in gadget mode, and
 - the USB cable is connected since before booting

The symptom is: about 6 seconds after configuring gadget mode the device is
disconnected and then re-enumerated. This happens only once per boot.

Investigation showed that in this configuration the charger detection code
turns off the PHY after 6 seconds. Patch 1 avoids this when a cable is
connected (VBUS present).

After patch 1 the connection is stable but communication stops after 6
seconds. this is addressed by patch 2.

The topic had been discussed in [0]. Thanks Alan and Minas for the
discussion and Louis for having found the 1st issue, leading to patch 1.

[0] https://lore.kernel.org/lkml/20250414185458.7767aabc@booty/

Luca

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
Louis Chauvet (1):
      phy: rockchip: inno-usb2: fix disconnection in gadget mode

Luca Ceresoli (1):
      phy: rockchip: inno-usb2: fix communication disruption in gadget mode

 drivers/phy/rockchip/phy-rockchip-inno-usb2.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
---
base-commit: 15240745d6cd14183d112249a9fff87fb968b859
change-id: 20250718-rk3308-fix-usb-gadget-phy-disconnect-d7de71fb28b4

Best regards,
-- 
Luca Ceresoli <luca.ceresoli@...tlin.com>