On Mon, Oct 16, 2023 at 08:11:08PM -0700, Bjorn Andersson wrote: > The USB IP-block found in most Qualcomm platforms is modelled in the > Linux kernel as 3 different independent device drivers, but as shown by > the already existing layering violations in the Qualcomm glue driver > they can not be operated independently. > > With the current implementation, the glue driver registers the core and > has no way to know when this is done. As a result, e.g. the suspend > callbacks needs to guard against NULL pointer dereferences when trying > to peek into the struct dwc3 found in the drvdata of the child. > > Missing from the upstream Qualcomm USB support is handling of role > switching, in which the glue needs to be notified upon DRD mode changes. > Several attempts has been made through the years to register callbacks > etc, but they always fall short when it comes to handling of the core's > probe deferral on resources etc. Nice to see this finally being worked on. It's not clear why mode-change notifications would be a problem though, as if you get such a notification, you know that core has been probed. > Furhtermore, the DeviceTree binding is a direct representation of the > Linux driver model, and doesn't necessarily describe "the USB IP-block". True. Johan
