People have had a long time to change and be aware of the correct return.
Some drivers now generate the correct return too.
diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.9rc3/Documentation/scsi/scsi_mid_low_api.txt linux-2.6.9rc3/Documentation/scsi/scsi_mid_low_api.txt
--- linux.vanilla-2.6.9rc3/Documentation/scsi/scsi_mid_low_api.txt 2004-09-30 16:13:07.221587568 +0100
+++ linux-2.6.9rc3/Documentation/scsi/scsi_mid_low_api.txt 2004-09-30 16:32:22.300988808 +0100
@@ -1091,10 +1091,6 @@
* mid level does not recognize it, then the LLD that controls
* the device receives the ioctl. According to recent Unix standards
* unsupported ioctl() 'cmd' numbers should return -ENOTTY.
- * However the mid level returns -EINVAL for unrecognized 'cmd'
- * numbers when this function is not supplied by the driver.
- * Unfortunately some applications expect -EINVAL and react badly
- * when -ENOTTY is returned; stick with -EINVAL.
*
* Optionally defined in: LLD
**/