linux-kernel - Re: [PATCH v4 6/9] usb: dwc3: save/restore OTG registers during suspend/resume

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Message-ID: <20150902144432.GH8299@saruman.tx.rr.com>
Date:	Wed, 2 Sep 2015 09:44:32 -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 6/9] usb: dwc3: save/restore OTG registers during
 suspend/resume

On Wed, Sep 02, 2015 at 05:24:21PM +0300, Roger Quadros wrote:
> Without this we loose OTG controller register context and malfunction
> after a system suspend-resume.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/usb/dwc3/core.c | 17 +++++++++++++++++
>  drivers/usb/dwc3/core.h |  6 +++++-
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 632ee53..684010c 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -56,6 +56,7 @@ void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
>  	reg = dwc3_readl(dwc->regs, DWC3_GCTL);
>  	reg &= ~(DWC3_GCTL_PRTCAPDIR(DWC3_GCTL_PRTCAP_OTG));
>  	reg |= DWC3_GCTL_PRTCAPDIR(mode);
> +	dwc->current_mode = mode;
>  	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
>  }
>  
> @@ -1443,6 +1444,14 @@ static int dwc3_suspend(struct device *dev)
>  
>  	spin_lock_irqsave(&dwc->lock, flags);
>  
> +	/* Save OTG state only if we're really using it */
> +	if (dwc->current_mode == DWC3_GCTL_PRTCAP_OTG) {
> +		dwc->ocfg = dwc3_readl(dwc->regs, DWC3_OCFG);
> +		dwc->octl = dwc3_readl(dwc->regs, DWC3_OCTL);
> +		dwc->oevt = dwc3_readl(dwc->regs, DWC3_OEVT);

oevt is what you use to clear pending IRQs, which means that ...

> +		dwc->oevten = dwc3_readl(dwc->regs, DWC3_OEVTEN);
> +	}
> +
>  	switch (dwc->dr_mode) {
>  	case USB_DR_MODE_PERIPHERAL:
>  	case USB_DR_MODE_OTG:
> @@ -1486,6 +1495,14 @@ static int dwc3_resume(struct device *dev)
>  	dwc3_event_buffers_setup(dwc);
>  	dwc3_writel(dwc->regs, DWC3_GCTL, dwc->gctl);
>  
> +	/* Restore OTG state only if we're really using it */
> +	if (dwc->current_mode == DWC3_GCTL_PRTCAP_OTG) {
> +		dwc3_writel(dwc->regs, DWC3_OCFG, dwc->ocfg);
> +		dwc3_writel(dwc->regs, DWC3_OCTL, dwc->octl);
> +		dwc3_writel(dwc->regs, DWC3_OEVT, dwc->oevt);

... you could be clearing pending IRQs right here.

> +		dwc3_writel(dwc->regs, DWC3_OEVTEN, dwc->oevten);
> +	}
> +
>  	switch (dwc->dr_mode) {
>  	case USB_DR_MODE_PERIPHERAL:
>  	case USB_DR_MODE_OTG:
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 129ef37..1115ce0 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -737,6 +737,7 @@ struct dwc3_scratchpad_array {
>   * @regs: base address for our registers
>   * @regs_size: address space size
>   * @oevten: otg interrupt enable mask copy
> + * @current_mode: current mode of operation written to PRTCAPDIR
>   * @nr_scratch: number of scratch buffers
>   * @num_event_buffers: calculated number of event buffers
>   * @u1u2: only used on revisions <1.83a for workaround
> @@ -858,9 +859,12 @@ struct dwc3 {
>  	/* used for suspend/resume */
>  	u32			dcfg;
>  	u32			gctl;
> -
> +	u32			ocfg;
> +	u32			octl;
> +	u32			oevt;
>  	u32			oevten;
>  
> +	u32			current_mode;
>  	u32			nr_scratch;
>  	u32			num_event_buffers;
>  	u32			u1u2;
> -- 
> 2.1.4
> 

-- 
balbi

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