default or selected kernelversion does not have config value CONFIG_BLK_DEV_OPTI621.
Result is shown for kernelversion 6.9.9

OPTi 82C621 chipset enhanced support

modulename: opti621.ko

configname: CONFIG_BLK_DEV_OPTI621

Linux Kernel Configuration
└─>Device Drivers
└─>ATA/ATAPI/MFM/RLL support (DEPRECATED)
└─>OPTi 82C621 chipset enhanced support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This is a driver for the OPTi 82C621 EIDE controller.
Please read the comments at the top of <file:drivers/ide/opti621.c>.

source code:
drivers/ide/opti621.c