I reverted the udelay change and left the extra ide_data_test call.

Now I get:
ide_data_test: wrote 0x0000 read 0xffff
ide_data_test: wrote 0xffff read 0xffff
ide_data_test: wrote 0xaaaa read 0xaaaa
ide_data_test: wrote 0x5555 read 0x5555
ide_data_test: wrote 0x0000 read 0x0000

so my last 4 match so I'm happy