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

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Message-Id: <DDNZMD1M6G49.1M47TZR3DVYQI@bootlin.com>
Date: Tue, 21 Oct 2025 14:09:39 +0200
From: "Luca Ceresoli" <luca.ceresoli@...tlin.com>
To: "Luca Ceresoli" <luca.ceresoli@...tlin.com>, "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>,
 "linux-phy" <linux-phy-bounces@...ts.infradead.org>
Subject: Re: [PATCH 0/2] phy: rockchip: inno-usb2: fix gadget mode
 disconnection after 6 seconds

Hello,

On Tue Jul 22, 2025 at 10:43 AM CEST, Luca Ceresoli wrote:
> 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>

Anything I should do to move forward with this work?

These two few-liner patches solve real-world bugs, there is no complaint
about them, and both the bug and the solution is explained as clearly as
the public documentation allows.

FWIW, this series applied cleany on current master
(v6.18-rc2-8-g6548d364a3e8).

Best regards,
Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com