Re: [PATCH v4 2/3] dt-bindings: usb: snps,dwc3: Add runtime-suspend-on-usb-suspend property

[Elson Serrao]

On 8/30/2023 11:29 PM, Krzysztof Kozlowski wrote:
> On 31/08/2023 05:01, Thinh Nguyen wrote:
> > On Wed, Aug 30, 2023, Krzysztof Kozlowski wrote:
> > > On 30/08/2023 06:31, Elson Serrao wrote:
> > > > On 8/29/2023 6:37 PM, Thinh Nguyen wrote:
> > > > > Just want to clarify, there are dwc3 properties and there are dt binding
> > > > > properties. Often the case that dt binding matches 1-to-1 with dwc3
> > > > > driver property. Now, we need to enhance the checkers so that the dwc3
> > > > > driver property to match cases where it is platform specific and through
> > > > > compatible string.
> > > >
> > > > Thank you for the clarification Thinh.
> > > > To confirm, we would need to modify the driver to parse a new compatible
> > > > string (say "snps,dwc3-ext-wakeup") and add .data field so that the
> > > > driver is aware that this particular platform supports external wakeup
> > > > detection.Right ?
> > >
> > > No, it's not then platform specific. You said it depends on each
> > > platform. Platform is Qualcomm SM8450 for example.
> >
> > Hi Elson,
> >
> > Use the compatible string of your platform.
> >
> > e.g.
> > if (dev->of_node) {
> > 	struct device_node *parent = of_get_parent(dev->of_node);
> >
> > 	dwc->no_disconnect_on_usb_suspend =
> > 		of_device_is_compatible(parent, "qcom,your-compatible-string") ||
> > 		of_device_is_compatible(parent, "some-other-platform");
> > }
> >
> > You need to enhance dwc3_get_properties(). This may get big as dwc3 adds
> > more properties. Perhaps you can help come up with ideas to keep this
> > clean. Perhaps we can separate this out of dwc3 core.c?

HI Thinh

Apologies for the delayed response.
Series 
https://patchwork.kernel.org/project/linux-usb/cover/1655094654-24052-1-git-send-email-quic_kriskura@xxxxxxxxxxx/ 
from Krishna K, introduced a dt property 'wakeup-source' which indicates 
a platforms capability to handle wakeup interrupts. Based on this 
property, glue drivers can inform dwc3 core that the device is wakeup 
capable through device_init_wakeup(). For example dwc3-qcom driver 
informs it like below as per the implementation done in the above series

	wakeup_source = of_property_read_bool(dev->of_node, "wakeup-source");
	device_init_wakeup(&pdev->dev, wakeup_source);
	device_init_wakeup(&qcom->dwc3->dev, wakeup_source);

The dwc3 core now can access this info through 
device_may_wakeup(dwc->dev) while checking for bus suspend scenario to 
know whether the platform is capable of detecting wakeup.

Please let me know your thoughts on this approach.

Thanks
Elson