Hello, for a new embedded board featuring a Microchip SAMA5D2 SoC (64 MiB SiP variant SAMA5D27C-D5M) we connected the third USB host port (HSIC only) with an USB3503 hub chip. This doesn't work out of the box with the Linux kernel currently, because neither the SoC nor the kernel does enable the HSIC interface by default. That SoC has three USB host ports, from the SAMA5D2 Series Datasheet [1] I learned there's a flag in an EHCI register, which has to be set to enable the HSIC interface on port C, the third port. (Section "41.7.14 EHCI: REG08 - HSIC Enable/Disable" of the datasheet.) I suppose that register is vendor specific. The register definitions in '/include/linux/usb/ehci_def.h' do not contain that register. Where would I add that register definition and set that flag in the kernel then? I suppose in the vendor specific ehci driver? That would be 'drivers/usb/host/ehci-atmel.c' right? Since that feature is optional (other boards don't need to turn on hsic on that port), some driver specific new device tree binding would be necessary, right? I suppose that would have to be documented in 'Documentation/ devicetree/bindings/usb/atmel-usb.txt' right? (Or that would have to be converted to yaml first?) Is this the right track? If yes, I'm going to develop patches for this. Otherwise any hint into the right direction are highly appreciated. FWIW, I'm not the first one struggling [2] with this problem. ;-) Greets Alex [1] https://www.microchip.com/en-us/product/ATSAMA5D27C-D5M#document-table [2] https://community.atmel.com/forum/sama5d2-using-hsic-under-linux
