linux-kernel - Re: [PATCH 1/2] usb: dwc2: add ep enabled flag to avoid double enable/disable

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Message-ID: <87zixii5ag.fsf@saruman.tx.rr.com>
Date:	Thu, 10 Dec 2015 11:26:15 -0600
From:	Felipe Balbi <balbi@...com>
To:	<changbin.du@...el.com>, <johnyoun@...opsys.com>
CC:	<gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	"Du, Changbin" <changbin.du@...el.com>
Subject: Re: [PATCH 1/2] usb: dwc2: add ep enabled flag to avoid double enable/disable


Hi,

changbin.du@...el.com writes:
> From: "Du, Changbin" <changbin.du@...el.com>
>
> Enabling a already enabled ep is illegal, because the ep may has trbs
> running. Reprogram the ep may break running transfer. So udc driver
> must avoid this happening by return an error -EBUSY. Gadget function
> driver also should avoid such things, but that is out of udc driver.
>
> Similarly, disable a disabled ep makes no sense, but no need return
> an error here.
>
> Signed-off-by: Du, Changbin <changbin.du@...el.com>
> ---
>  drivers/usb/dwc2/core.h   |  1 +
>  drivers/usb/dwc2/gadget.c | 20 +++++++++++++++++++-
>  2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index a66d3cb..cf7eccd 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -162,6 +162,7 @@ struct dwc2_hsotg_ep {
>  	unsigned char           mc;
>  	unsigned char           interval;
>  
> +	unsigned int		enabled:1;
>  	unsigned int            halted:1;
>  	unsigned int            periodic:1;
>  	unsigned int            isochronous:1;
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 0abf73c..586bbcd 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -2423,6 +2423,7 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
>  	/* enable, but don't activate EP0in */
>  	dwc2_writel(dwc2_hsotg_ep0_mps(hsotg->eps_out[0]->ep.maxpacket) |
>  	       DXEPCTL_USBACTEP, hsotg->regs + DIEPCTL0);
> +	hsotg->eps_out[0]->enabled = 1;
>  
>  	dwc2_hsotg_enqueue_setup(hsotg);
>  
> @@ -2680,6 +2681,14 @@ static int dwc2_hsotg_ep_enable(struct usb_ep *ep,
>  		return -EINVAL;
>  	}
>  
> +	spin_lock_irqsave(&hsotg->lock, flags);
> +	if (hs_ep->enabled) {
> +		dev_warn(hsotg->dev, "%s: ep %s already enabled\n",
> +			__func__, hs_ep->name);

this is a rather serious condition. I'd rather use dev_WARN_ONCE():

	if (dev_WARN_ONCE(hsotg->dev, hs_ep->enabled,
           	"ep %s already enabled\n", hs_ep->name)) {

-- 
balbi

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