On Tue, Mar 28, 2023 at 02:18:16PM +0200, Johan Hovold wrote: > On Tue, Mar 28, 2023 at 03:35:01PM +0530, Manivannan Sadhasivam wrote: > > On Tue, Mar 28, 2023 at 11:46:36AM +0200, Johan Hovold wrote: > > > On Sat, Mar 25, 2023 at 10:22:17PM +0530, Manivannan Sadhasivam wrote: > > > > dwc3-qcom driver is capable of doing runtime PM on its own, but currently > > > > it requires userspace intervention to enable it. But there is no harm in > > > > letting the driver to enable runtime PM on its own. So let's get rid of the > > > > "pm_runtime_forbid()" and make sure that the dependency is maintained with > > > > child devices using "pm_suspend_ignore_children(dev, false)". > > > > > > Well, the potential harm is that these paths have hardly been tested so > > > enabling it by default is a risk (e.g. as you noticed when trying to > > > enable this by default). And especially if we don't address the layering > > > violations first. > > > > > > > I certainly tested this on a couple of boards with host and gadget mode and > > noticed no issue (except one issue noticed by Steev on a docking station with > > display but that should be related to orientation switch). > > > > Even if we allow runtime PM on this driver, still userspace needs to enable it > > for dwc3 and xhci drivers. So this essentially reduces one step in that process > > if someone tries to enable runtime PM for usb intentionally. So I don't forsee a > > potential harm here. > > Well this whole driver is a mess so I don't have any problem imagining > ways in which things can break. ;) > > > > > Also during remove(), the device needs to be waken up first if it was > > > > runtime suspended. Finally, pm_runtime_allow() can be removed. > > > > > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > > > --- > > > > drivers/usb/dwc3/dwc3-qcom.c | 5 +++-- > > > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c > > > > index f1059dfcb0e8..5f26bb66274f 100644 > > > > --- a/drivers/usb/dwc3/dwc3-qcom.c > > > > +++ b/drivers/usb/dwc3/dwc3-qcom.c > > > > @@ -920,7 +920,7 @@ static int dwc3_qcom_probe(struct platform_device *pdev) > > > > qcom->is_suspended = false; > > > > pm_runtime_set_active(dev); > > > > pm_runtime_enable(dev); > > > > - pm_runtime_forbid(dev); > > > > + pm_suspend_ignore_children(dev, false); > > > > > > There's no need to explicitly disable ignore-children as that is the > > > default. > > > > > > > Other dwc drivers were doing it, so I thought someone (maintainer) wanted to > > explicitly disable ignore_children. But if that's not the case, I can remove it. > > Yeah, please remove it. I doubt these runtime pm implementations have > gotten much review. > > Note how several dwc3 glue drivers just do an unconditional get in > probe(), which means that these paths are probably never exercised at > all and effectively amounts to that pm_runtime_forbid() you are removing > here. > > Probably there to tick off "runtime pm" on some internal project > manager's list of "features". > Agree. > > > > return 0; > > > > > > > > @@ -948,6 +948,8 @@ static int dwc3_qcom_remove(struct platform_device *pdev) > > > > struct device *dev = &pdev->dev; > > > > int i; > > > > > > > > + pm_runtime_get_sync(dev); > > > > > > This call needs to be balanced. But this is a fix for a bug in the > > > current implementation that should go in a separate patch. > > > > > > > Ok. For balancing I could add pm_runtime_put_noidle() before pm_runtime_disable. > > You should do it after disabling runtime pm. > May I know why? Thanks, Mani > > > > + > > > > device_remove_software_node(&qcom->dwc3->dev); > > > > of_platform_depopulate(dev); > > > > > > > > @@ -960,7 +962,6 @@ static int dwc3_qcom_remove(struct platform_device *pdev) > > > > dwc3_qcom_interconnect_exit(qcom); > > > > reset_control_assert(qcom->resets); > > > > > > > > - pm_runtime_allow(dev); > > > > pm_runtime_disable(dev); > > > > > > > > return 0; > > Johan -- மணிவண்ணன் சதாசிவம்
