[v3,1/3] usb: dwc3: pci: Add GPIO lookup table on platforms without ACPI GPIO resources

[Felipe Balbi <balbi@kernel.org>]

Hans de Goede <hdegoede@redhat.com> writes:

> Hi,
>
> On 10-06-18 16:01, Hans de Goede 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.
>> 
>> The good news it that all boards (*) use the same GPIOs.
>> 
>> This commit fixes the ULPI phy not woring by adding a gpiod_lookup_table
>> call which adds a hardcoded mapping for BYT devices. Note that the mapping
>> added by gpiod_add_lookup_table is a fallback mapping, so boards which
>> properly provide GPIO resources in the ACPI firmware-node resources
>> will not use this.
>> 
>> *) Except for the first revision of the evalulation-kit, which normal users
>> don't have
>> 
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>> Changes in v3:
>> -Add the mapping with gpiod_add_lookup_table() unconditionally on BYT
>>   devices, as they are only used after checking for GPIO resources in ACPI
>
> Ping? AFAIK this series is ready for merging now and it is necessary to
> make gadget mode work on all Bay Trail devices which support gadget
> mode.

now queued for v4.19