Re: sdparm cannot start or stop SATA disks

[Jeff Garzik <jgarzik@pobox.com>]

Douglas Gilbert wrote:
> I could have a go at the SCSI half of it. According to
> SAT, START STOP UNIT should only be allowed for non-packet
> ATA devices. I assume your SATAPI code will the bypass
> libata-scsi.c SAT layer.

Mostly.  There is still a few translation bits in there.  99% bypass, 
not 100%.


> SAT suggests libata should issue a ATA STANDBY (sector=0)
> to "stop" the device. I can't see the STANDBY command (0xE2)
> defined anywhere in libata or the ide subsystem (or their
> headers).

I'm sure you're capable of adding an enum to linux/ata.h :)


> The action to start the SATA device depends on the power
> mode of the SATA device:
>   - SLEEP: send a hardware or software reset: that should
>     get it to ACTIVE or STANDBY mode
>   - STANDBY or IDLE: send a (READ) VERIFY (sector=0) ATA
>     to the command
>   - ACTIVE: I assume this would be a nop
> 
> The START STOP UNIT SCSI command also has an "IMMED"iate
> bit. That could just be ignored initially.
> 
> Is half a patch any use?

Sure.

	Jeff