On Thu, Jun 7, 2018 at 1:38 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Bay Trail / BYT SoCs do not have a builtin device-mode phy, instead > they require an external ULPI phy for device-mode. > > Only some BYT devices have an external phy, but even on those devices > device-mode is not working because the dwc3 does not see the phy. > > The problem is that the ACPI fwnode for the dwc3 does not contain the > expected GPIO resources for the GPIOs connected to the chip-select and > reset pins of the phy. > > I've found the workaround which some Android x86 kernels use for this: > https://github.com/BORETS24/Kernel-for-Asus-Zenfone-2/blob/master/arch/x86/platform/intel-mid/device_libs/pci/platform_usb_otg.c > Which boils down to hardcoding the GPIOs for these devices. > > This commit adds a gpiod_lookup_table adding the mappings from Android, > and installs this table on BYT system with their BIOS vendor DMI string > set to "INSYDE Corp.". This seems to indicate that a (mostly) unmodified > version of the reference design BIOS is used. 3 out of the 20 BYT tablets > which I have for testing have an external ULPI phy and all 3 models use > this vendor string. > + vendor = dmi_get_system_info(DMI_BIOS_VENDOR); > + if (vendor && strcmp(vendor, "INSYDE Corp.") == 0) { > + gpiod_add_lookup_table(&platform_bytcr_gpios); > + dwc->gpio_mapping_added = true; > + } I understand that my proposal might sound a bit overkill, though, I would rather go with normal dmi tables and call back there. P.S. Though, I would be okay with this as long as Felipe fine. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
