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Date: Fri, 21 Jul 2017 14:15:17 +0530
From: Manu Gautam <mgautam@...eaurora.org>
To: Baolin Wang <baolin.wang@...aro.org>, balbi@...nel.org,
gregkh@...uxfoundation.org
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
linaro-kernel@...ts.linaro.org, broonie@...nel.org
Subject: Re: [PATCH] usb: dwc3: Support the dwc3 host suspend/resume
Hi,
On 7/21/2017 12:28 PM, Baolin Wang wrote:
> For some mobile devices with strict power management, we also want to
> suspend the host when the slave was detached for power saving. Thus
> adding the host suspend/resume functions to support this requirement.
USB/PM core already takes care of suspending root-HUB/XHCI when
no device connected.
>
> We will issue the pm_suspend_ignore_children() for the dwc3 device,
> since we will resume the child device (xHCI device) in runtime resume
> callback (dwc3_host_resume()) of dwc3 device, now the dwc3 device's
> runtime state is not RPM_ACTIVE, which will block to resume its
> child device (xHCI device). Add ignore children flag can avoid this
> situation.
This defeats the basic purpose of runtime PM. Without ignore_children
once USB bus is suspended, dwc3 gets suspended and then dwc3 glue device.
Only requirement I see from the patch is to resume XHCI/root-hub on
dwc3 resume. I am sure there must be other way to deal with that e.g.
doing same from glue driver by using a wq or use pm_request_resume()
>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
> drivers/usb/dwc3/core.c | 26 +++++++++++++++++++++++++-
> drivers/usb/dwc3/core.h | 7 +++++++
> drivers/usb/dwc3/host.c | 15 +++++++++++++++
> 3 files changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 326b302..2be7ddc 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1193,6 +1193,7 @@ static int dwc3_probe(struct platform_device *pdev)
> pm_runtime_use_autosuspend(dev);
> pm_runtime_set_autosuspend_delay(dev, DWC3_DEFAULT_AUTOSUSPEND_DELAY);
> pm_runtime_enable(dev);
> + pm_suspend_ignore_children(dev, true);
> ret = pm_runtime_get_sync(dev);
> if (ret < 0)
> goto err1;
> @@ -1292,15 +1293,27 @@ static int dwc3_remove(struct platform_device *pdev)
> static int dwc3_suspend_common(struct dwc3 *dwc)
What is the trigger for runtime suspend now that you have ignore_children set.
> {
> 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);
With DRD/OTG, if current mode is device and dwc3->xhci won't be valid.
You can refer to the patch that I pushed to address this.
> + 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;
> @@ -1322,12 +1335,23 @@ 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 ea910ac..9b5a4eb 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1193,11 +1193,18 @@ static inline bool dwc3_is_usb31(struct dwc3 *dwc)
> #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
> int dwc3_host_init(struct dwc3 *dwc);
> void dwc3_host_exit(struct dwc3 *dwc);
> +int dwc3_host_suspend(struct dwc3 *dwc);
> +int dwc3_host_resume(struct dwc3 *dwc);
> #else
> static inline int dwc3_host_init(struct dwc3 *dwc)
> { return 0; }
> static inline void dwc3_host_exit(struct dwc3 *dwc)
> { }
> +
> +static inline int dwc3_host_suspend(struct dwc3 *dwc)
> +{ return 0; }
> +static inline int dwc3_host_resume(struct dwc3 *dwc)
> +{ return 0; }
> #endif
>
> #if IS_ENABLED(CONFIG_USB_DWC3_GADGET) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index 76f0b0d..3fa4414 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -16,6 +16,7 @@
> */
>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>
> #include "core.h"
>
> @@ -151,3 +152,17 @@ void dwc3_host_exit(struct dwc3 *dwc)
> dev_name(dwc->dev));
> platform_device_unregister(dwc->xhci);
> }
> +
> +int dwc3_host_suspend(struct dwc3 *dwc)
> +{
> + struct device *xhci = &dwc->xhci->dev;
> +
> + return pm_runtime_suspend(xhci);
If ignore_children is not marked then xhci would indeed be suspended.
> +}
> +
> +int dwc3_host_resume(struct dwc3 *dwc)
> +{
> + struct device *xhci = &dwc->xhci->dev;
> +
> + return pm_runtime_resume(xhci);
Other than what I pushed in my patch -
("usb: dwc3: Don't reinitialize core during host bus-suspend/resume")
Just performing pm_request_resume or handling same in dwc3 glue
driver should be sufficient.
Also, what is trigger for runtime_resume for your platform?
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