linux-kernel - Re: [PATCH v9 1/2] usb: dwc2: assert phy reset when waking up in rk3288 platform

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Message-ID: <4ee5817d-0076-9974-8b0e-182a0241e1f5@synopsys.com>
Date:   Fri, 21 Oct 2016 12:27:32 -0700
From:   John Youn <John.Youn@...opsys.com>
To:     Randy Li <ayaka@...lik.info>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:     "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@...ech.de" <heiko@...ech.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "randy.li@...k-chips.com" <randy.li@...k-chips.com>
Subject: Re: [PATCH v9 1/2] usb: dwc2: assert phy reset when waking up in
 rk3288 platform

On 10/20/2016 11:38 AM, Randy Li wrote:
> 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.h      |  1 +
>  drivers/usb/dwc2/core_intr.c | 11 +++++++++++
>  drivers/usb/dwc2/platform.c  |  9 +++++++++
>  3 files changed, 21 insertions(+)
> 
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 2a21a04..e91ddbc 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -859,6 +859,7 @@ struct dwc2_hsotg {
>  	unsigned int ll_hw_enabled:1;
>  
>  	struct phy *phy;
> +	struct work_struct phy_rst_work;
>  	struct usb_phy *uphy;
>  	struct dwc2_hsotg_plat *plat;
>  	struct regulator_bulk_data supplies[ARRAY_SIZE(dwc2_hsotg_supply_names)];
> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
> index d85c5c9..c3d2168 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"))
> +				schedule_work(&hsotg->phy_rst_work);
> +
>  			mod_timer(&hsotg->wkp_timer,
>  				  jiffies + msecs_to_jiffies(71));
>  		} else {
> diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> index 8e1728b..65953cf 100644
> --- a/drivers/usb/dwc2/platform.c
> +++ b/drivers/usb/dwc2/platform.c
> @@ -366,6 +366,14 @@ int dwc2_lowlevel_hw_disable(struct dwc2_hsotg *hsotg)
>  	return ret;
>  }
>  
> +/* Only used to reset usb phy at interrupter runtime */
> +static void dwc2_reset_phy_work(struct work_struct *data)
> +{
> +	struct dwc2_hsotg *hsotg = container_of(data, struct dwc2_hsotg,
> +			phy_rst_work);
> +	phy_reset(hsotg->phy);
> +}
> +
>  static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
>  {
>  	int i, ret;
> @@ -410,6 +418,7 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
>  			return ret;
>  		}
>  	}
> +	INIT_WORK(&hsotg->phy_rst_work, dwc2_reset_phy_work);
>  
>  	if (!hsotg->phy) {
>  		hsotg->uphy = devm_usb_get_phy(hsotg->dev, USB_PHY_TYPE_USB2);
> 

Hi Randy,

This fails compile if CONFIG_GENERIC_PHY is disabled. I think you need
to make a fix to your phy_reset patch first.

Regards,
John