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

[Baolin Wang]

Hi Felipe,

On 18 August 2016 at 20:25, Felipe Balbi <balbi@xxxxxxxxxx> wrote:
>
> Hi,
>
> Baolin Wang <baolin.wang@xxxxxxxxxx> writes:
>> Hi Felipe,
>>
>> On 18 August 2016 at 15:33, Felipe Balbi <balbi@xxxxxxxxxx> wrote:
>>>
>>> Hi,
>>>
>>> Baolin Wang <baolin.wang@xxxxxxxxxx> 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@xxxxxxxxxx>
>>>> ---
>>>>  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?
>>
>> xhci-plat.c did not set the runtime PM callbacks, how can we issued
>> xhci_supend() by runtime PM from dwc3?
>
> wouldn't it be nicer to just initialize PM runtime callbacks from
> xhci-plat? It just needs to be added and verified, right?

Yes, you are right. Alan and Peter also suggested me to implement the
runtime PM callbacks for xhci-plat. I am also testing this and I will
send out the patch if it works well. So please ignore this patch.
Thanks for your comments.

-- 
Baolin.wang
Best Regards