On Tue, Jan 14, 2025 at 5:04 PM Bjorn Andersson <andersson@xxxxxxxxxx> wrote: > > On Tue, Jan 14, 2025 at 11:44:52AM -0600, Rob Herring wrote: > > On Mon, Jan 13, 2025 at 09:11:33PM -0800, 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 proper 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. > > > > > > Furhtermore, the DeviceTree binding is a direct representation of the > > > Linux driver model, and doesn't necessarily describe "the USB IP-block". > > > > > > This series therefor attempts to flatten the driver split, and operate > > > the glue and core out of the same platform_device instance. And in order > > > to do this, the DeviceTree representation of the IP block is flattened. > > > > > > To avoid littering the dwc3-qcom driver with the migration code - which > > > we should be able to drop again in a LTS or two - this is now placed in > > > drivers/of/overlays. > > > > > > A patch to convert a single platform - sc8280xp - is included in the > > > series. The broader conversion will be submitted in a follow up series. > > > > Is it not possible to use the same overlays also fixup the .dts files at > > build time? > > > > I presume so. What would the benefit of that be, over fixing up the > source asap? The overlays would live with all the other dts files (I think kbuild can add built-in dtbs from arch/*/boot/dts/). We can test at build time they actually apply, and ensure the new dtb matches what the fixup overlay creates. Rob
