linux-kernel - Re: [PATCH] usb: dwc3: usb/dwc3: fake dissconnect event when turn off pullup

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Message-ID: <488a2557-9a02-290c-f6e8-95f633c9a732@cogentembedded.com>
Date:	Wed, 27 Apr 2016 15:04:24 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	changbin.du@...el.com, balbi@...nel.org
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Du@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3: usb/dwc3: fake dissconnect event when turn off
 pullup

Hello.

On 4/27/2016 11:29 AM, changbin.du@...el.com wrote:

> From: "Du, Changbin" <changbin.du@...el.com>
>
> The dwc3 controller can't generate a disconnect event after it is
> stopped. Thus gadget dissconnect callback is not invoked when do
> soft dissconnect. Call dissconnect here to workaround this issue.

    "Disconnect" everywhere.

> Note, most time we still see disconnect be called that because
> it is invoked by dwc3_gadget_reset_interrupt(). But if we
> disconnect cable once pullup disabled quickly, issue can be
> observed.
>
> Signed-off-by: Du, Changbin <changbin.du@...el.com>
> ---
>  drivers/usb/dwc3/gadget.c | 33 ++++++++++++++++++++++++---------
>  1 file changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 8e4a1b1..cd73187 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
[...]
> @@ -1575,6 +1584,21 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  	is_on = !!is_on;
>
>  	spin_lock_irqsave(&dwc->lock, flags);
> +	/**
> +	 * WORKAROUND: The dwc3 controller can't generate a disconnect
> +	 * event after it is stopped. Thus gadget dissconnect callback
> +	 * is not invoked when do soft dissconnect. Call dissconnect
> +	 * here to workaround this issue.

    "Disconnect" everywhere.

> +	 * Note, most time we still see disconnect be called that because

    I couldn't parse that.

> +	 * it is invoked by dwc3_gadget_reset_interrupt(). But if we
> +	 * disconnect cable once pullup disabled quickly, issue can be
> +	 * observed.
> +	 */
> +	if (!is_on && (dwc->gadget.speed != USB_SPEED_UNKNOWN)) {
> +		dev_dbg(dwc->dev, "fake dissconnect event on pullup off\n");

    Disconnect.

> +		dwc3_disconnect_gadget(dwc);
> +		dwc->gadget.speed = USB_SPEED_UNKNOWN;
> +	}
>  	ret = dwc3_gadget_run_stop(dwc, is_on, false);
>  	spin_unlock_irqrestore(&dwc->lock, flags);
>
[...]

MBR, Sergei