linux-kernel - RE: [PATCH] usb: gadget: udc: renesas_usb3: Fix host to USB_ROLE

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Date:   Mon, 31 Jan 2022 00:23:25 +0000
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     Adam Ford <aford173@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:     "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "cstevens@...conembedded.com" <cstevens@...conembedded.com>,
        "aford@...conembedded.com" <aford@...conembedded.com>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Biju Das <biju.das@...renesas.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb: gadget: udc: renesas_usb3: Fix host to USB_ROLE_NONE
 transition

Hi Adam-san,

Thank you for the patch!

> From: Adam Ford, Sent: Saturday, January 29, 2022 7:36 AM
> 
> The support the external role switch a variety of situations were
> addressed, but the transition from USB_ROLE_HOST to USB_ROLE_NONE
> leaves the host up which can cause some error messages when
> switching from host to none, to gadget, to none, and then back
> to host again.

I think so. An external role switch in this driver is possible to
enter the role to USB_ROLE_NONE. (Just a record for me: in other words,
the "internal" role switch didn't enter the role to USB_ROLE_NONE.)

>  xhci-hcd ee000000.usb: Abort failed to stop command ring: -110
>  xhci-hcd ee000000.usb: xHCI host controller not responding, assume dead
>  xhci-hcd ee000000.usb: HC died; cleaning up
>  usb 4-1: device not accepting address 6, error -108
>  usb usb4-port1: couldn't allocate usb_device
> 
> After this happens it will not act as a host again.
> Fix this by releasing the host mode when transitioning to USB_ROLE_NONE.
> 
> Fixes: 0604160d8c0b ("usb: gadget: udc: renesas_usb3: Enhance role switch support")
> Signed-off-by: Adam Ford <aford173@...il.com>
> 
> diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> index 57d417a7c3e0..601829a6b4ba 100644
> --- a/drivers/usb/gadget/udc/renesas_usb3.c
> +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> @@ -2378,6 +2378,8 @@ static void handle_ext_role_switch_states(struct device *dev,
>  	switch (role) {
>  	case USB_ROLE_NONE:
>  		usb3->connection_state = USB_ROLE_NONE;
> +		if (cur_role == USB_ROLE_HOST)
> +			device_release_driver(host);

The handle_ext_role_switch_states() with role = USB_ROLE_NONE seems
to be called multiple times. So, we have to avoid multiple calling of
device_release_driver() somehow.

Best regards,
Yoshihiro Shimoda

>  		if (usb3->driver)
>  			usb3_disconnect(usb3);
>  		usb3_vbus_out(usb3, false);
> --
> 2.32.0