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

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Date:   Sat, 15 Oct 2016 23:07:36 +0800
From:   陈豪 <jacobchen110@...il.com>
To:     Randy Li <ayaka@...lik.info>
Cc:     linux-usb@...r.kernel.org, John.Youn@...opsys.com, kishon@...com,
        felipe.balbi@...ux.intel.com, mark.rutland@....com,
        devicetree@...r.kernel.org, Heiko Stuebner <heiko@...ech.de>,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, robh+dt@...nel.org,
        randy.li@...k-chips.com
Subject: Re: [PATCH v8 2/3] usb: dwc2: assert phy reset when waking up in
 rk3288 platform

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？