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

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Date:	Thu, 3 Sep 2015 16:54:14 +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 6/9] usb: dwc3: save/restore OTG registers during
 suspend/resume

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On 02/09/15 17:44, Felipe Balbi wrote:
> 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.

Good catch. So we can't really restore this register.
I'll remove this line.

> 
>> +		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
>>
> 

- --
cheers,
- -roger
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