Re: [PATCH 4/4] usb: dwc3: core: Support the dwc3 host suspend/resume

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Baolin Wang <baolin.wang@linaro.org> writes:
> For some mobile devices with strict power management, we also want to suspend
> the host when the slave is detached for power saving.
>
> Thus we add the host suspend/resume functions to support this requirement, and
> we also should enable the 'XHCI_SLOW_SUSPEND' quirk for extraordinary delay when
> suspending the xhci.
>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
>  drivers/usb/dwc3/Kconfig |    7 +++++++
>  drivers/usb/dwc3/core.c  |   25 ++++++++++++++++++++++++-
>  drivers/usb/dwc3/core.h  |   15 +++++++++++++++
>  drivers/usb/dwc3/host.c  |   32 ++++++++++++++++++++++++++++++++
>  4 files changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
> index a64ce1c..725d2bd 100644
> --- a/drivers/usb/dwc3/Kconfig
> +++ b/drivers/usb/dwc3/Kconfig
> @@ -45,6 +45,13 @@ config USB_DWC3_DUAL_ROLE
>  	  This is the default mode of working of DWC3 controller where
>  	  both host and gadget features are enabled.
>  
> +config USB_DWC3_HOST_SUSPEND
> +	bool "Choose if the host (xhci) can be suspend/resume"
> +	depends on USB_DWC3_HOST=y || USB_DWC3_DUAL_ROLE=y
> +	help
> +	  We can suspend the host when the slave is detached for power saving,
> +	  and resume the host when one slave is attached.
> +
>  endchoice
>  
>  comment "Platform Glue Driver Support"
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 1485480..5140b4d 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1103,15 +1103,27 @@ static int dwc3_remove(struct platform_device *pdev)
>  static int dwc3_suspend_common(struct dwc3 *dwc)
>  {
>  	unsigned long	flags;
> +	int		ret;
>  
>  	switch (dwc->dr_mode) {
>  	case USB_DR_MODE_PERIPHERAL:
> +		spin_lock_irqsave(&dwc->lock, flags);
> +		dwc3_gadget_suspend(dwc);
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +		break;
>  	case USB_DR_MODE_OTG:
> +		ret = dwc3_host_suspend(dwc);
> +		if (ret)
> +			return ret;
> +
>  		spin_lock_irqsave(&dwc->lock, flags);
>  		dwc3_gadget_suspend(dwc);
>  		spin_unlock_irqrestore(&dwc->lock, flags);
>  		break;
>  	case USB_DR_MODE_HOST:
> +		ret = dwc3_host_suspend(dwc);
> +		if (ret)
> +			return ret;
>  	default:
>  		/* do nothing */
>  		break;
> @@ -1133,12 +1145,23 @@ static int dwc3_resume_common(struct dwc3 *dwc)
>  
>  	switch (dwc->dr_mode) {
>  	case USB_DR_MODE_PERIPHERAL:
> +		spin_lock_irqsave(&dwc->lock, flags);
> +		dwc3_gadget_resume(dwc);
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +		break;
>  	case USB_DR_MODE_OTG:
> +		ret = dwc3_host_resume(dwc);
> +		if (ret)
> +			return ret;
> +
>  		spin_lock_irqsave(&dwc->lock, flags);
>  		dwc3_gadget_resume(dwc);
>  		spin_unlock_irqrestore(&dwc->lock, flags);
> -		/* FALLTHROUGH */
> +		break;
>  	case USB_DR_MODE_HOST:
> +		ret = dwc3_host_resume(dwc);
> +		if (ret)
> +			return ret;
>  	default:
>  		/* do nothing */
>  		break;
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 45d6de5..0ba203e 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1177,4 +1177,19 @@ static inline void dwc3_ulpi_exit(struct dwc3 *dwc)
>  { }
>  #endif
>  
> +#if IS_ENABLED(USB_DWC3_HOST_SUSPEND)
> +int dwc3_host_suspend(struct dwc3 *dwc);
> +int dwc3_host_resume(struct dwc3 *dwc);
> +#else
> +static inline int dwc3_host_suspend(struct dwc3 *dwc)
> +{
> +	return 0;
> +}
> +
> +static inline int dwc3_host_resume(struct dwc3 *dwc)
> +{
> +	return 0;
> +}
> +#endif
> +
>  #endif /* __DRIVERS_USB_DWC3_CORE_H */
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index 2e960ed..2ec3eff 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -17,8 +17,11 @@
>  
>  #include <linux/platform_device.h>
>  #include <linux/usb/xhci_pdriver.h>
> +#include <linux/usb.h>
> +#include <linux/usb/hcd.h>
>  
>  #include "core.h"
> +#include "../host/xhci.h"
>  
>  int dwc3_host_init(struct dwc3 *dwc)
>  {
> @@ -91,6 +94,8 @@ int dwc3_host_init(struct dwc3 *dwc)
>  	memset(&pdata, 0, sizeof(pdata));
>  
>  	pdata.usb3_lpm_capable = dwc->usb3_lpm_capable;
> +	/* dwc3 controller need an extraordinary delay when suspending xhci. */
> +	pdata.usb3_slow_suspend = 1;
>  
>  	ret = platform_device_add_data(xhci, &pdata, sizeof(pdata));
>  	if (ret) {
> @@ -128,3 +133,30 @@ void dwc3_host_exit(struct dwc3 *dwc)
>  			  dev_name(&dwc->xhci->dev));
>  	platform_device_unregister(dwc->xhci);
>  }
> +
> +int dwc3_host_suspend(struct dwc3 *dwc)
> +{
> +	struct usb_hcd *hcd = dev_get_drvdata(&dwc->xhci->dev);
> +	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> +	int ret, cnt = 20;
> +
> +try_again:
> +	 /* We should wait for xhci bus has been into suspend mode firstly. */
> +	ret = xhci_suspend(xhci, device_may_wakeup(&dwc->xhci->dev));
> +	if (ret && --cnt > 0) {
> +		dev_warn(dwc->dev, "xhci suspend failed %d, try again...\n",
> +			 ret);
> +		msleep(200);
> +		goto try_again;
> +	}
> +
> +	return ret;
> +}
> +
> +int dwc3_host_resume(struct dwc3 *dwc)
> +{
> +	struct usb_hcd *hcd = dev_get_drvdata(&dwc->xhci->dev);
> +	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> +
> +	return xhci_resume(xhci, 0);
> +}

This is wrong. XHCI is a child of dwc3, when dwc3 suspends,
xhci_supend() has already been called. Why isn't it called for you?

-- 
balbi

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