Zero power optical drive support (ZPODD) is finally coming to the Linux kernel. Support for ZPODD will be available in the 3.9 kernel.
ZPODD aims to reduce power consumption on SATA Slimline Optical Disk Drives (ODDs). Both drawer and slot OODs are supported. The goal is to cut off the power supply to the optical drive when it is not in use. When the user wants to use the drive, the power supply is resumed. For more information, see the Mount Fuji 8 Revision 1.0 Specification. The Mount Fuji group consists of optical disc drive manufacturers, operating system vendors, independent software developers, and other optical disc affiliated companies. It operates under the SFF Committee which is an ad hoc group formed to address storage industry needs in a prompt manner.
The specification modified ODD SATA slimline connector pin assignments to allow a device to notify the host that it requires Device Attention (DA). The host platform must connect the ODD device’s DA signal to a general purpose I/O pin. For PCs, this is one of the GPEx_STS bits in the ACPI Fixed Hardware register interface (See Section 4.7.4 of the ACPI Specification). For system-on-a-chip (SOC), this is any GPIO pin, as long as that pin is exposed by a GPIO driver.
In Linux 3.9, an ODD can be enabled for ZPODD if the following three conditions are satisfied:
- The ODD supports device attention
- The host platform can runtime power off the ODD through ACPI
- The ODD is either a slot or tray (drawer) type
The OOD will be placed in suspend state if:
- For a tray ODD, no media is inside and the door closed
- For a slot ODD, no media is inside
The OOD can exit suspend state either though a software command or by one of the
- For a tray ODD, by pressing the eject button
- For a slot ODD, by inserting a disc
A new kernel config, CONFIG_SATA_ZPODD, was added to selectively build ZPODD code. Aaron Lu
ZPOOD is also supported in Microsoft Windows 8.