SPI pinctrl information doesn't show up correctly although SPI bus function properly, is this correct? I expect "AF5" show up instead of "Analog" for pin function.

On my custom board, I configured PZ0, PZ1, PZ2 for SPI1 with device tree, and linux kernel probed successfully and populate spidev node and it works fine, but if look at debug information in /sys/kernel/debug/pinctrl/, it populate something like "pin 400 (PZ0): device 44004000.spi function analog group PZ0", I expect "AF5" for pin function instead of "analog", especailly for this case it has configured as SPI alternate pin already. Is this a kernel bug or some trick I have to do with device tree?