On 13-11-05 11:23 AM, Phillip Susi wrote:
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On 11/5/2013 10:56 AM, Douglas Gilbert wrote:
I think that you might find that almost any SCSI command
(translated to its ATA equivalent command) will wake up a SATA
disk. Perhaps just this sequence: fd = open(<ata_bloc_device>) ;
close(fd) ; is sufficient.
No, otherwise hdparm, udisks, etc would not be able to issue the CHECK
POWER command without waking the disk. Most commands do wake the
drive, but as far as I can see, nobody is sending down any, and more
importantly, the wake is happening within the kernel pm resume path,
not by userspace after resume.
hdparm is quite capable of using a pass-through device
to access disks. That allows it (and smartmontools) to
access physical disks in a RAID when the block layer
can only see the logical disk out front.
udisks is not that smart.
Perhaps you need to start debugging around here:
static int sd_resume(struct device *dev)
{
struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
int ret = 0;
if (!sdkp->device->manage_start_stop)
goto done;
sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
ret = sd_start_stop_device(sdkp, 1);
done:
scsi_disk_put(sdkp);
return ret;
}
to work out if it is spun up before or after that call.
Doug Gilbert
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