linux-kernel - Re: [PATCH v3 6/8] usb: dwc3: Increase DWC3 controller halt timeout

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Date:   Tue, 16 Aug 2022 17:51:46 -0700
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.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>
Subject: Re: [PATCH v3 6/8] usb: dwc3: Increase DWC3 controller halt timeout

Hi Thinh,

On 8/16/2022 5:34 PM, Thinh Nguyen wrote:
> On 8/15/2022, Wesley Cheng wrote:
>> Since EP0 transactions need to be completed before the controller halt
>> sequence is finished, this may take some time depending on the host and the
>> enabled functions.  Increase the controller halt timeout, so that we give
>> the controller sufficient time to handle EP0 transfers.  Remove the need
>> for making dwc3_gadget_suspend() and dwc3_gadget_resume() to be called in
>> a spinlock.
> 
> Sounds like the removal of the spin_lock and the increase of halt
> timeout are 2 separate change. It would be nice to separate this patch
> since the $subject only indicates 1 of them.
> 

Sure, I'll split these up.

>>
>> Suggested-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
>> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
>> ---
>>   drivers/usb/dwc3/core.c   | 4 ----
>>   drivers/usb/dwc3/gadget.c | 8 +++++++-
>>   2 files changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index c5c238ab3083..23e123a1ab5f 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1976,9 +1976,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>   	case DWC3_GCTL_PRTCAP_DEVICE:
>>   		if (pm_runtime_suspended(dwc->dev))
>>   			break;
>> -		spin_lock_irqsave(&dwc->lock, flags);
>>   		dwc3_gadget_suspend(dwc);
>> -		spin_unlock_irqrestore(&dwc->lock, flags);
>>   		synchronize_irq(dwc->irq_gadget);
>>   		dwc3_core_exit(dwc);
>>   		break;
>> @@ -2039,9 +2037,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>>   			return ret;
>>   
>>   		dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>> -		spin_lock_irqsave(&dwc->lock, flags);
>>   		dwc3_gadget_resume(dwc);
>> -		spin_unlock_irqrestore(&dwc->lock, flags);
>>   		break;
>>   	case DWC3_GCTL_PRTCAP_HOST:
>>   		if (!PMSG_IS_AUTO(msg) && !device_can_wakeup(dwc->dev)) {
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 7b66a54250a0..b2668a83cc29 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -2444,7 +2444,7 @@ static void __dwc3_gadget_set_speed(struct dwc3 *dwc)
>>   static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
>>   {
>>   	u32			reg;
>> -	u32			timeout = 500;
>> +	u32			timeout = 100;
>>   
>>   	if (pm_runtime_suspended(dwc->dev))
>>   		return 0;
>> @@ -2477,6 +2477,7 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
>>   	dwc3_gadget_dctl_write_safe(dwc, reg);
>>   
>>   	do {
>> +		msleep(20);
> 
> Polling interval of 20ms seems a bit much. Can we use usleep_range()
> between 1-2ms?
> 
> Thanks,
> Thinh

Sounds good. Let me reduce the interval gap and resubmit.

Thanks
Wesley Cheng

> 
>>   		reg = dwc3_readl(dwc->regs, DWC3_DSTS);
>>   		reg &= DWC3_DSTS_DEVCTRLHLT;
>>   	} while (--timeout && !(!is_on ^ !reg));
>> @@ -4520,12 +4521,17 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
>>   
>>   int dwc3_gadget_suspend(struct dwc3 *dwc)
>>   {
>> +	unsigned long flags;
>> +
>>   	if (!dwc->gadget_driver)
>>   		return 0;
>>   
>>   	dwc3_gadget_run_stop(dwc, false, false);
>> +
>> +	spin_lock_irqsave(&dwc->lock, flags);
>>   	dwc3_disconnect_gadget(dwc);
>>   	__dwc3_gadget_stop(dwc);
>> +	spin_unlock_irqrestore(&dwc->lock, flags);
>>   
>>   	return 0;
>>   }
>