linux-kernel - Re: [PATCH v4 8/9] usb: dwc3: core: Prevent otg events from disabling themselves

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Date:	Thu, 3 Sep 2015 16:54:47 +0300
From:	Roger Quadros <rogerq@...com>
To:	<balbi@...com>
CC:	<tony@...mide.com>, <Joao.Pinto@...opsys.com>,
	<sergei.shtylyov@...entembedded.com>, <peter.chen@...escale.com>,
	<jun.li@...escale.com>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>
Subject: Re: [PATCH v4 8/9] usb: dwc3: core: Prevent otg events from disabling
 themselves

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On 02/09/15 17:47, Felipe Balbi wrote:
> On Wed, Sep 02, 2015 at 05:24:23PM +0300, Roger Quadros wrote:
>> There is a race happening during dwc3_drd_init() that causes
>> otg events to get disabled. This is what happens.
>>
>> dwc3_otg_irq() happens immediately when PRTCAP is set to OTG,
>> even though OEVTEN is 0. This is because BIT 31 IRQ of
>> OEVT can't be disabled by OEVTEN.
>> We configure OEVTEN in dwc3_otg_init() but dwc3_otg_irq() has
>> already saved OEVTEN as 0 into dwc->oevten. So finally when
>> dwc3_irq_thread_irq() is called we save 0 into OEVTEN
>> thus disabling OTG irqs forever.
>>
>> We fix this by disabling IRQs when configuring OEVTEN in
>> dwc3_otg_init().
>>
>> Signed-off-by: Roger Quadros <rogerq@...com>
> 
> can't you just merge this patch into the one which introduced the bug to
> start with ?

Yes, I'll do that.

> 
>> ---
>>  drivers/usb/dwc3/core.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 684010c..654aebf 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -921,6 +921,7 @@ static int dwc3_drd_init(struct dwc3 *dwc)
>>  	int ret, id, vbus;
>>  	struct usb_otg_caps *otgcaps = &dwc->otg_config.otg_caps;
>>  	u32 reg;
>> +	unsigned long flags;
>>  
>>  	otgcaps->otg_rev = 0;
>>  	otgcaps->hnp_support = false;
>> @@ -993,6 +994,8 @@ try_otg_core:
>>  		goto error;
>>  	}
>>  
>> +	spin_lock_irqsave(&dwc->lock, flags);
>> +
>>  	/* we need to set OTG to get events from OTG core */
>>  	dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
>>  	/* GUSB2PHYCFG0.SusPHY=0 */
>> @@ -1018,6 +1021,8 @@ try_otg_core:
>>  	/* OCTL.PeriMode = 1 */
>>  	dwc3_writel(dwc->regs, DWC3_OCTL, DWC3_OCTL_PERIMODE);
>>  
>> +	spin_unlock_irqrestore(&dwc->lock, flags);
>> +
>>  	dwc3_otg_fsm_sync(dwc);
>>  	usb_otg_sync_inputs(dwc->fsm);
>>  
>> -- 
>> 2.1.4
>>
> 
- --
cheers,
- -roger
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