Recently I attempted using a USB to RS232+LPT adapter based on MCS7715 chipset. Driver for MOS7720 also supports LPT part, but it is enabled as a boolean option USB_SERIAL_MOS7715_PARPORT. I'd like to make this configurable through OpenWrt package configuration. I tried adding a Kconfig symbol which selects KERNEL_USB_SERIAL_MOS7715_PARPORT (as stated on the wiki and here: How to add a Kernel Config setting to package makefile) but to no avail.
I also tried the approach used in package/kernel/mac80211/ath.mk, for example as done for ATH_USER_REGD, but didn't work out either.
I've put my patch here: https://github.com/Leo-PL/openwrt/commit/180ff196ac3ee26bb84a27b5410e46f6ba373ca7
I think I should append KCONFIG variable under KernelPackage/usb-serial-mos7720 with USB_SERIAL_MOS7715_PARPORT=y somehow, but right now I don't see a clear way to do this from /config.
Any help would be greatly appreciated.