| Message ID | 1651740973-7944-3-git-send-email-quic_kriskura@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | USB DWC3 host wake up support from system suspend | expand |
On Thu, May 05, 2022 at 02:26:09PM +0530, Krishna Kurapati wrote: > device_wakeup_path() tells if any of the children devices needs > wakeup. Use this hint to enable/disable wakeup of our device. This > helps the parent device of xhci-plat (like sysdev) to retrieve > the wakeup setting via device_wakeup_path(). > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > --- > drivers/usb/host/xhci-plat.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > index 649ffd8..ad585fa 100644 > --- a/drivers/usb/host/xhci-plat.c > +++ b/drivers/usb/host/xhci-plat.c > @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) > if (pm_runtime_suspended(dev)) > pm_runtime_resume(dev); > > + if (device_wakeup_path(dev)) { > + if (!device_may_wakeup(dev)) > + device_wakeup_enable(dev); > + } else { > + if (device_may_wakeup(dev)) > + device_wakeup_disable(dev); > + } This code is not self-explantatory and deserves a comment. Enabling/disabling wakeup for the purpose if signalling is a bit of a hack. It might be an acceptable hack as long as it has no side effects. However with the current implementation the wakeup state of the xHCI can be different after resuming than it was before going to suspend: after boot grep -h xhci /sys/class/wakeup/*/name => xhci-hcd.14.auto after suspend w/o wakeup capable device grep -h xhci /sys/class/wakeup/*/name => no results after suspend with wakeup capable device grep -h xhci /sys/class/wakeup/*/name => xhci-hcd.14.auto The hack shouldn't alter the wakeup state 'persistently', i.e. you'll have to restore it on resume, as in Pavan does in his reply to '[PATCH v14 2/7] PM / wakeup: Add device_children_wakeup_capable()' (it needs to be done conditionally though).
On Fri, May 06, 2022 at 08:36:31AM -0700, Matthias Kaehlcke wrote: > On Thu, May 05, 2022 at 02:26:09PM +0530, Krishna Kurapati wrote: > > device_wakeup_path() tells if any of the children devices needs > > wakeup. Use this hint to enable/disable wakeup of our device. This > > helps the parent device of xhci-plat (like sysdev) to retrieve > > the wakeup setting via device_wakeup_path(). > > > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > > --- > > drivers/usb/host/xhci-plat.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > index 649ffd8..ad585fa 100644 > > --- a/drivers/usb/host/xhci-plat.c > > +++ b/drivers/usb/host/xhci-plat.c > > @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) > > if (pm_runtime_suspended(dev)) > > pm_runtime_resume(dev); > > > > + if (device_wakeup_path(dev)) { > > + if (!device_may_wakeup(dev)) > > + device_wakeup_enable(dev); > > + } else { > > + if (device_may_wakeup(dev)) > > + device_wakeup_disable(dev); > > + } > > This code is not self-explantatory and deserves a comment. > > Enabling/disabling wakeup for the purpose if signalling is a bit of a > hack. It might be an acceptable hack as long as it has no side effects. > However with the current implementation the wakeup state of the xHCI can > be different after resuming than it was before going to suspend: > > after boot > grep -h xhci /sys/class/wakeup/*/name > => xhci-hcd.14.auto > > after suspend w/o wakeup capable device > grep -h xhci /sys/class/wakeup/*/name > => no results > > after suspend with wakeup capable device > grep -h xhci /sys/class/wakeup/*/name > => xhci-hcd.14.auto > > The hack shouldn't alter the wakeup state 'persistently', i.e. you'll have > to restore it on resume, as in Pavan does in his reply to '[PATCH v14 2/7] > PM / wakeup: Add device_children_wakeup_capable()' (it needs to be done > conditionally though). I am worried that we are not doing the right thing here. why should the xhci-plat goes against the wishes of the user space policy here? Can we NOT just do anything here? If some one wants xhci-plat to wakeup all the time, dwc3 will be configured to wakeup the system provided that the support is available. This way we don't break any existing users of xhci-plat i.e not enabling wakeup from the kernel. Thanks, Pavan
On Mon, May 09, 2022 at 09:08:43AM +0530, Pavan Kondeti wrote: > On Fri, May 06, 2022 at 08:36:31AM -0700, Matthias Kaehlcke wrote: > > On Thu, May 05, 2022 at 02:26:09PM +0530, Krishna Kurapati wrote: > > > device_wakeup_path() tells if any of the children devices needs > > > wakeup. Use this hint to enable/disable wakeup of our device. This > > > helps the parent device of xhci-plat (like sysdev) to retrieve > > > the wakeup setting via device_wakeup_path(). > > > > > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > > > --- > > > drivers/usb/host/xhci-plat.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > > index 649ffd8..ad585fa 100644 > > > --- a/drivers/usb/host/xhci-plat.c > > > +++ b/drivers/usb/host/xhci-plat.c > > > @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) > > > if (pm_runtime_suspended(dev)) > > > pm_runtime_resume(dev); > > > > > > + if (device_wakeup_path(dev)) { > > > + if (!device_may_wakeup(dev)) > > > + device_wakeup_enable(dev); > > > + } else { > > > + if (device_may_wakeup(dev)) > > > + device_wakeup_disable(dev); > > > + } > > > > This code is not self-explantatory and deserves a comment. > > > > Enabling/disabling wakeup for the purpose if signalling is a bit of a > > hack. It might be an acceptable hack as long as it has no side effects. > > However with the current implementation the wakeup state of the xHCI can > > be different after resuming than it was before going to suspend: > > > > after boot > > grep -h xhci /sys/class/wakeup/*/name > > => xhci-hcd.14.auto > > > > after suspend w/o wakeup capable device > > grep -h xhci /sys/class/wakeup/*/name > > => no results > > > > after suspend with wakeup capable device > > grep -h xhci /sys/class/wakeup/*/name > > => xhci-hcd.14.auto > > > > The hack shouldn't alter the wakeup state 'persistently', i.e. you'll have > > to restore it on resume, as in Pavan does in his reply to '[PATCH v14 2/7] > > PM / wakeup: Add device_children_wakeup_capable()' (it needs to be done > > conditionally though). > > I am worried that we are not doing the right thing here. why should the > xhci-plat goes against the wishes of the user space policy here? Can we NOT > just do anything here? If some one wants xhci-plat to wakeup all the time, > dwc3 will be configured to wakeup the system provided that the support is > available. This way we don't break any existing users of xhci-plat i.e not > enabling wakeup from the kernel. > Krishna, can we please drop this patch and use device_wakeup_path() and verify the following cases. 1. one of the downstream USB device supports wakeup and xhci-plat wakeup is enabled 2. one of the downstream USB device supports wakeup and xhci-plat wakeup is disabled 3. none of the downstream USB device supports wakeup (or disable) and xhci-plat wakeup is enabled. 4. none of the downstream USB device supports wakeup (or disable) and xhci-plat wakeup is disabled. We don't want to enable xhci-plat wakeup capability like we do in this patch and potentially break any other platform. Lets leave the policy to the user space and rely on wakeup path to see if we can achieve the desired result. Thanks, Pavan
On Wed, May 11, 2022 at 07:21:01AM +0530, Pavan Kondeti wrote: > On Mon, May 09, 2022 at 09:08:43AM +0530, Pavan Kondeti wrote: > > On Fri, May 06, 2022 at 08:36:31AM -0700, Matthias Kaehlcke wrote: > > > On Thu, May 05, 2022 at 02:26:09PM +0530, Krishna Kurapati wrote: > > > > device_wakeup_path() tells if any of the children devices needs > > > > wakeup. Use this hint to enable/disable wakeup of our device. This > > > > helps the parent device of xhci-plat (like sysdev) to retrieve > > > > the wakeup setting via device_wakeup_path(). > > > > > > > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > > > > --- > > > > drivers/usb/host/xhci-plat.c | 8 ++++++++ > > > > 1 file changed, 8 insertions(+) > > > > > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > > > index 649ffd8..ad585fa 100644 > > > > --- a/drivers/usb/host/xhci-plat.c > > > > +++ b/drivers/usb/host/xhci-plat.c > > > > @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) > > > > if (pm_runtime_suspended(dev)) > > > > pm_runtime_resume(dev); > > > > > > > > + if (device_wakeup_path(dev)) { > > > > + if (!device_may_wakeup(dev)) > > > > + device_wakeup_enable(dev); > > > > + } else { > > > > + if (device_may_wakeup(dev)) > > > > + device_wakeup_disable(dev); > > > > + } > > > > > > This code is not self-explantatory and deserves a comment. > > > > > > Enabling/disabling wakeup for the purpose if signalling is a bit of a > > > hack. It might be an acceptable hack as long as it has no side effects. > > > However with the current implementation the wakeup state of the xHCI can > > > be different after resuming than it was before going to suspend: > > > > > > after boot > > > grep -h xhci /sys/class/wakeup/*/name > > > => xhci-hcd.14.auto > > > > > > after suspend w/o wakeup capable device > > > grep -h xhci /sys/class/wakeup/*/name > > > => no results > > > > > > after suspend with wakeup capable device > > > grep -h xhci /sys/class/wakeup/*/name > > > => xhci-hcd.14.auto > > > > > > The hack shouldn't alter the wakeup state 'persistently', i.e. you'll have > > > to restore it on resume, as in Pavan does in his reply to '[PATCH v14 2/7] > > > PM / wakeup: Add device_children_wakeup_capable()' (it needs to be done > > > conditionally though). > > > > I am worried that we are not doing the right thing here. why should the > > xhci-plat goes against the wishes of the user space policy here? Can we NOT > > just do anything here? If some one wants xhci-plat to wakeup all the time, > > dwc3 will be configured to wakeup the system provided that the support is > > available. This way we don't break any existing users of xhci-plat i.e not > > enabling wakeup from the kernel. > > > Krishna, > > can we please drop this patch and use device_wakeup_path() and verify the > following cases. > > 1. one of the downstream USB device supports wakeup and xhci-plat wakeup is enabled > 2. one of the downstream USB device supports wakeup and xhci-plat wakeup is > disabled > 3. none of the downstream USB device supports wakeup (or disable) and > xhci-plat wakeup is enabled. > 4. none of the downstream USB device supports wakeup (or disable) and > xhci-plat wakeup is disabled. I wonder if we couldn't keep this simpler: if the dwc3 is wakeup capable keep the PHYs/core powered, otherwise power them down. Similar to what commit 689bf72c6e0d ("usb: dwc3: Don't reinitialize core during host bus-suspend/resume") intended, but with the additonal check for wakeup capability. We now know that the PHYs need to be powered down on some SoCs to allow the SoC to reach its low power mode during suspend: commit c4a5153e87fdf6805f63ff57556260e2554155a5 Author: Manu Gautam <mgautam@codeaurora.org> Date: Thu Jan 18 16:54:30 2018 +0530 usb: dwc3: core: Power-off core/PHYs on system_suspend in host mode Commit 689bf72c6e0d ("usb: dwc3: Don't reinitialize core during host bus-suspend/resume") updated suspend/resume routines to not power_off and reinit PHYs/core for host mode. It broke platforms that rely on DWC3 core to power_off PHYs to enter low power state on system suspend. With wakeup capable controllers this is apparently not an issue, otherwise the SoC wouldn't be able to enter its low power state when wakeup is enabled.
On Wed, May 11, 2022 at 08:54:25AM -0700, Matthias Kaehlcke wrote: > On Wed, May 11, 2022 at 07:21:01AM +0530, Pavan Kondeti wrote: > > On Mon, May 09, 2022 at 09:08:43AM +0530, Pavan Kondeti wrote: > > > On Fri, May 06, 2022 at 08:36:31AM -0700, Matthias Kaehlcke wrote: > > > > On Thu, May 05, 2022 at 02:26:09PM +0530, Krishna Kurapati wrote: > > > > > device_wakeup_path() tells if any of the children devices needs > > > > > wakeup. Use this hint to enable/disable wakeup of our device. This > > > > > helps the parent device of xhci-plat (like sysdev) to retrieve > > > > > the wakeup setting via device_wakeup_path(). > > > > > > > > > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > > > > > --- > > > > > drivers/usb/host/xhci-plat.c | 8 ++++++++ > > > > > 1 file changed, 8 insertions(+) > > > > > > > > > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c > > > > > index 649ffd8..ad585fa 100644 > > > > > --- a/drivers/usb/host/xhci-plat.c > > > > > +++ b/drivers/usb/host/xhci-plat.c > > > > > @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) > > > > > if (pm_runtime_suspended(dev)) > > > > > pm_runtime_resume(dev); > > > > > > > > > > + if (device_wakeup_path(dev)) { > > > > > + if (!device_may_wakeup(dev)) > > > > > + device_wakeup_enable(dev); > > > > > + } else { > > > > > + if (device_may_wakeup(dev)) > > > > > + device_wakeup_disable(dev); > > > > > + } > > > > > > > > This code is not self-explantatory and deserves a comment. > > > > > > > > Enabling/disabling wakeup for the purpose if signalling is a bit of a > > > > hack. It might be an acceptable hack as long as it has no side effects. > > > > However with the current implementation the wakeup state of the xHCI can > > > > be different after resuming than it was before going to suspend: > > > > > > > > after boot > > > > grep -h xhci /sys/class/wakeup/*/name > > > > => xhci-hcd.14.auto > > > > > > > > after suspend w/o wakeup capable device > > > > grep -h xhci /sys/class/wakeup/*/name > > > > => no results > > > > > > > > after suspend with wakeup capable device > > > > grep -h xhci /sys/class/wakeup/*/name > > > > => xhci-hcd.14.auto > > > > > > > > The hack shouldn't alter the wakeup state 'persistently', i.e. you'll have > > > > to restore it on resume, as in Pavan does in his reply to '[PATCH v14 2/7] > > > > PM / wakeup: Add device_children_wakeup_capable()' (it needs to be done > > > > conditionally though). > > > > > > I am worried that we are not doing the right thing here. why should the > > > xhci-plat goes against the wishes of the user space policy here? Can we NOT > > > just do anything here? If some one wants xhci-plat to wakeup all the time, > > > dwc3 will be configured to wakeup the system provided that the support is > > > available. This way we don't break any existing users of xhci-plat i.e not > > > enabling wakeup from the kernel. > > > > > Krishna, > > > > can we please drop this patch and use device_wakeup_path() and verify the > > following cases. > > > > 1. one of the downstream USB device supports wakeup and xhci-plat wakeup is enabled > > 2. one of the downstream USB device supports wakeup and xhci-plat wakeup is > > disabled > > 3. none of the downstream USB device supports wakeup (or disable) and > > xhci-plat wakeup is enabled. > > 4. none of the downstream USB device supports wakeup (or disable) and > > xhci-plat wakeup is disabled. > > I wonder if we couldn't keep this simpler: if the dwc3 is wakeup capable keep > the PHYs/core powered, otherwise power them down. Similar to what commit > 689bf72c6e0d ("usb: dwc3: Don't reinitialize core during host > bus-suspend/resume") intended, but with the additonal check for wakeup > capability. We now know that the PHYs need to be powered down on some SoCs > to allow the SoC to reach its low power mode during suspend: > > > commit c4a5153e87fdf6805f63ff57556260e2554155a5 > Author: Manu Gautam <mgautam@codeaurora.org> > Date: Thu Jan 18 16:54:30 2018 +0530 > > usb: dwc3: core: Power-off core/PHYs on system_suspend in host mode > > Commit 689bf72c6e0d ("usb: dwc3: Don't reinitialize core during > host bus-suspend/resume") updated suspend/resume routines to not > power_off and reinit PHYs/core for host mode. > It broke platforms that rely on DWC3 core to power_off PHYs to > enter low power state on system suspend. > > > With wakeup capable controllers this is apparently not an issue, otherwise > the SoC wouldn't be able to enter its low power state when wakeup is > enabled. Agree to your suggestion. Thanks for your inputs. Thanks, Pavan
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c index 649ffd8..ad585fa 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -415,6 +415,14 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) if (pm_runtime_suspended(dev)) pm_runtime_resume(dev); + if (device_wakeup_path(dev)) { + if (!device_may_wakeup(dev)) + device_wakeup_enable(dev); + } else { + if (device_may_wakeup(dev)) + device_wakeup_disable(dev); + } + ret = xhci_priv_suspend_quirk(hcd); if (ret) return ret;
device_wakeup_path() tells if any of the children devices needs wakeup. Use this hint to enable/disable wakeup of our device. This helps the parent device of xhci-plat (like sysdev) to retrieve the wakeup setting via device_wakeup_path(). Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> --- drivers/usb/host/xhci-plat.c | 8 ++++++++ 1 file changed, 8 insertions(+)