On Wed, Jan 22, 2025 at 09:07:43PM -0600, Bjorn Andersson wrote: > On Wed, Jan 15, 2025 at 12:51:42PM -0600, Rob Herring wrote: > > 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. > > > > That does sounds tempting, in particular since it sounds like it would > provide us with dt-validation of the end result. > > But, the build-time overlaid dtb files wouldn't be complete, as I > programmatically transition some of the properties - to "fix" that I'd > have to provide an overlay per board. > > Second, it was my intention to transition all the boards to the new > binding as soon as possible, to avoid adding more overlays when new > boards are added. So any support-system we build up for this, would be > immediately obsoleted. Ok, fair enough. I would still prefer the overlays live in arch/*/boot/dts/qcom/ even if we don't do the rest. Rob
