linux-kernel - Re: [PATCH v2 3/5] usb: dwc3: gadget: Adjust IRQ management during soft disconnect/connect

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Message-ID: <fbfc9328-418c-4c5e-4553-993331b20cb6@synopsys.com>
Date:   Thu, 14 Jul 2022 17:38:36 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <quic_wcheng@...cinc.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Subject: Re: [PATCH v2 3/5] usb: dwc3: gadget: Adjust IRQ management during
 soft disconnect/connect

On 7/12/2022, Wesley Cheng wrote:
> Local interrupts are currently being disabled as part of aquiring the
> spin lock before issuing the endxfer command.  Leave interrupts enabled, so
> that EP0 events can continue to be processed.  Also, ensure that there are
> no pending interrupts before attempting to handle any soft
> connect/disconnect.
>
> Fixes: 861c010a2ee1 ("usb: dwc3: gadget: Refactor pullup()")
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
>   drivers/usb/dwc3/gadget.c | 21 ++++++++++++---------
>   1 file changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index a455f8d4631d..ee85b773e3fe 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1674,6 +1674,7 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
>   static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool interrupt)
>   {
>   	struct dwc3_gadget_ep_cmd_params params;
> +	struct dwc3 *dwc = dep->dwc;
>   	u32 cmd;
>   	int ret;
>   
> @@ -1682,7 +1683,9 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
>   	cmd |= interrupt ? DWC3_DEPCMD_CMDIOC : 0;
>   	cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
>   	memset(&params, 0, sizeof(params));
> +	spin_unlock(&dwc->lock);
>   	ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
> +	spin_lock(&dwc->lock);
>   	WARN_ON_ONCE(ret);
>   	dep->resource_index = 0;
>   
> @@ -2029,12 +2032,11 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
>   	struct dwc3_ep			*dep = to_dwc3_ep(ep);
>   	struct dwc3			*dwc = dep->dwc;
>   
> -	unsigned long			flags;
>   	int				ret = 0;
>   
>   	trace_dwc3_ep_dequeue(req);
>   
> -	spin_lock_irqsave(&dwc->lock, flags);
> +	spin_lock(&dwc->lock);
>   
>   	list_for_each_entry(r, &dep->cancelled_list, list) {
>   		if (r == req)
> @@ -2073,7 +2075,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
>   		request, ep->name);
>   	ret = -EINVAL;
>   out:
> -	spin_unlock_irqrestore(&dwc->lock, flags);
> +	spin_unlock(&dwc->lock);
>   
>   	return ret;
>   }
> @@ -2489,9 +2491,7 @@ static int __dwc3_gadget_start(struct dwc3 *dwc);
>   
>   static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
>   {
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&dwc->lock, flags);
> +	spin_lock(&dwc->lock);
>   	dwc->connected = false;
>   
>   	/*
> @@ -2506,10 +2506,10 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
>   
>   		reinit_completion(&dwc->ep0_in_setup);
>   
> -		spin_unlock_irqrestore(&dwc->lock, flags);
> +		spin_unlock(&dwc->lock);
>   		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
>   				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
> -		spin_lock_irqsave(&dwc->lock, flags);
> +		spin_lock(&dwc->lock);
>   		if (ret == 0)
>   			dev_warn(dwc->dev, "timed out waiting for SETUP phase\n");
>   	}
> @@ -2523,7 +2523,7 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
>   	 */
>   	dwc3_stop_active_transfers(dwc);
>   	__dwc3_gadget_stop(dwc);
> -	spin_unlock_irqrestore(&dwc->lock, flags);
> +	spin_unlock(&dwc->lock);
>   
>   	/*
>   	 * Note: if the GEVNTCOUNT indicates events in the event buffer, the
> @@ -2569,6 +2569,8 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>   		return 0;
>   	}
>   
> +	synchronize_irq(dwc->irq_gadget);
> +
>   	if (!is_on) {
>   		ret = dwc3_gadget_soft_disconnect(dwc);
>   	} else {
> @@ -3729,6 +3731,7 @@ void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
>   	 */
>   
>   	__dwc3_stop_active_transfer(dep, force, interrupt);
> +
>   }
>   
>   static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)

Hi Greg,

Please don't pick up this patch yet. We're still in discussion with 
this. I have some concern with unlocking/locking when sending End 
Transfer command. For example, this patch may cause issues with 
DWC3_EP_END_TRANSFER_PENDING checks.

Hi Wesley,

Did you try out my suggestion yet?

Thanks,
Thinh