linux-kernel - Re: [PATCH v8 2/3] usb: dwc2: assert phy reset when waking up in rk3288 platform

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Message-ID: <d8f43ae4-bfca-ce37-772d-a61b77f5493a@synopsys.com>
Date:   Wed, 19 Oct 2016 15:58:27 -0700
From:   John Youn <John.Youn@...opsys.com>
To:     陈豪 <jacobchen110@...il.com>,
        Randy Li <ayaka@...lik.info>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "John.Youn@...opsys.com" <John.Youn@...opsys.com>,
        "kishon@...com" <kishon@...com>,
        "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Heiko Stuebner <heiko@...ech.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "randy.li@...k-chips.com" <randy.li@...k-chips.com>
Subject: Re: [PATCH v8 2/3] usb: dwc2: assert phy reset when waking up in
 rk3288 platform

On 10/15/2016 8:07 AM, 陈豪 wrote:
> 2016-09-25 2:50 GMT+08:00 Randy Li <ayaka@...lik.info>:
>> On the rk3288 USB host-only port (the one that's not the OTG-enabled
>> port) the PHY can get into a bad state when a wakeup is asserted (not
>> just a wakeup from full system suspend but also a wakeup from
>> autosuspend).
>>
>> We can get the PHY out of its bad state by asserting its "port reset",
>> but unfortunately that seems to assert a reset onto the USB bus so it
>> could confuse things if we don't actually deenumerate / reenumerate the
>> device.
>>
>> We can also get the PHY out of its bad state by fully resetting it using
>> the reset from the CRU (clock reset unit) in chip, which does a more full
>> reset.  The CRU-based reset appears to actually cause devices on the bus
>> to be removed and reinserted, which fixes the problem (albeit in a hacky
>> way).
>>
>> It's unfortunate that we need to do a full re-enumeration of devices at
>> wakeup time, but this is better than alternative of letting the bus get
>> wedged.
>>
>> Signed-off-by: Randy Li <ayaka@...lik.info>
>> ---
>>  drivers/usb/dwc2/core_intr.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
>> index d85c5c9..af27edc 100644
>> --- a/drivers/usb/dwc2/core_intr.c
>> +++ b/drivers/usb/dwc2/core_intr.c
>> @@ -345,6 +345,7 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
>>  static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>  {
>>         int ret;
>> +       struct device_node *np = hsotg->dev->of_node;
>>
>>         /* Clear interrupt */
>>         dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
>> @@ -379,6 +380,16 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
>>                         /* Restart the Phy Clock */
>>                         pcgcctl &= ~PCGCTL_STOPPCLK;
>>                         dwc2_writel(pcgcctl, hsotg->regs + PCGCTL);
>> +
>> +                       /*
>> +                        * It is a quirk in Rockchip RK3288, causing by
>> +                        * a hardware bug. This will propagate out and
>> +                        * eventually we'll re-enumerate the device.
>> +                        * Not great but the best we can do.
>> +                        */
>> +                       if (of_device_is_compatible(np, "rockchip,rk3288-usb"))
>> +                               phy_reset(hsotg->phy);
> 
> It will call mutex_lock in phy_reset.
> 
> 
>> +
>>                         mod_timer(&hsotg->wkp_timer,
>>                                   jiffies + msecs_to_jiffies(71));
>>                 } else {
>> --
>> 2.7.4
>>
> 
> What is the status of this patch？
> Sleeping calls(phy_reset ==> mutex) shouldn't be used in irq handler.
> Randy will correct that？
> 

Yes, that's right, I missed that.

It will have to be fixed.

Regards,
John