[2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Felipe Balbi <balbi@kernel.org>]

Hi,

Roger Quadros <rogerq@ti.com> writes:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
>  drivers/usb/dwc3/core.c | 31 +++++++++++++++++++++++++++++++
>  drivers/usb/dwc3/core.h |  5 +++++
>  drivers/usb/dwc3/drd.c  | 10 ++++++----
>  3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>  #endif /* CONFIG_PM */
>  
>  #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> +	struct dwc3	*dwc = dev_get_drvdata(dev);
> +	unsigned long	flags;
> +
> +	if (dwc->dr_mode == USB_DR_MODE_OTG) {
> +		spin_lock_irqsave(&dwc->lock, flags);
> +		dwc->dr_keep_role = true;
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +	}
> +
> +	return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> +	struct dwc3	*dwc = dev_get_drvdata(dev);
> +	unsigned long	flags;
> +
> +	if (dwc->dr_mode == USB_DR_MODE_OTG) {
> +		spin_lock_irqsave(&dwc->lock, flags);
> +		dwc->dr_keep_role = false;
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +		dwc3_drd_update(dwc);
> +	}
> +}

wouldn't it be far easier to just disable OTG IRQ in prepare? and,
perhaps, also flush_work_sync() ?