CONFIG_GPIO_SWNODE_UNDEFINED (not configurable)

configname: CONFIG_GPIO_SWNODE_UNDEFINED

Linux Kernel Configuration
└─>Device Drivers
└─>GPIO Support
└─>GPIO_SWNODE_UNDEFINED
In linux kernel since version 4.19.318 (release Date: 2024-07-18)  
This adds a special place holder for software nodes to contain an
undefined GPIO reference, this is primarily used by SPI to allow a
list of GPIO chip selects to mark a certain chip select as being
controlled the SPI device's internal chip select mechanism and not
a GPIO.

depends
CONFIG_GPIOLIB