Below is my knowledge regarding to the DMA. Just for your reference. It may be wrong.
1. The default setting of DMA for CDROM is disabled, user could modify it via the device manager.
2. The capibility was first coming from the ATA identify command issued to ATA device(HDD, CDROM, ...), if the device did not support, no way to enable it. Normally, this value is reflected to the value of DeviceTimingMode which the ATA driver got in each boot.
3. If the driver vendor implement a miniport driver, it could limited the capibility by having a mask. The value reflected in DeviceTimingModeAllowed.
4. While the CRC error occured over six times, the DMA mode must be degraded, the new value will update into DeviceTimingModeAllowed. this value will not be reset except the driver was uninstall, then re-install.
5. In ACPI mode, if the BIOS implement the _GTM method, this value will AND the capibility got from identification command to gain the value of DeviceTimingMode.

Your system may have the _GTM method to disable the DMA capibility for CDROM devices, in such case, no way to run DMA mode.