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SubjectRe: [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@soulik.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@soulik.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?

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