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

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Message-ID: <458d5e4f-95ad-22f5-02ec-bb39c4e69ad9@rock-chips.com>
Date:   Thu, 20 Oct 2016 08:50:40 +0800
From:   Randy Li <randy.li@...k-chips.com>
To:     John Youn <John.Youn@...opsys.com>,
        陈豪 <jacobchen110@...il.com>,
        Randy Li <ayaka@...lik.info>
Cc:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "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>
Subject: Re: [PATCH v8 2/3] usb: dwc2: assert phy reset when waking up in
 rk3288 platform



On 10/20/2016 06:58 AM, John Youn wrote:
> 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.
I am still thinking a method to instead it.
>
> Regards,
> John
>
>

-- 
Randy Li
The third produce department
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