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

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Message-ID: <20150902144705.GI8299@saruman.tx.rr.com>
Date:	Wed, 2 Sep 2015 09:47:05 -0500
From:	Felipe Balbi <balbi@...com>
To:	Roger Quadros <rogerq@...com>
CC:	<balbi@...com>, <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

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 ?

> ---
>  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
> 

-- 
balbi

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