2013/6/10 Oliver Neukum <oneu...@suse.de> > > On Sunday 09 June 2013 16:28:21 Morales, Alejandra wrote: > > > I did a test with an external USB hard drive, checking the runtime power > > state before and after issuing a sleep command with hdparm -Y. The drive > > effectively spinned down, but the runtime power state didn't change from > > active to suspended. > > Hard disks, as opposed to USB storage devices, don't do kernel based runtime > PM. > If you give a drive commands by hdparm, implementation is the job of the disk > and > nothing else in the system learns about it. > > > - Do scsi device drivers implement the runtime_status updates when drives > > effectively change their state? > > - Is runtime power management supported by net devices? > > > > Any answer would be really appreciated. Thanks in advance. > > You are approaching this from the wrong side. "net device" is the function of > a device. It is effectively impossible to even define what runtime PM would > mean > in that case. You need to approach the question from the side of > implementation. > Is your device USB, PCI, SCSI, FibreChannel, ... ? > > As far as SCSI is concerned, yes SCSI devices can do runtime PM (in principle) > The most mature implementation is USB. > > You need to furthermore realise that there are forms of runtime PM independent > of the generic kernel based runtime PM (hdparm, USB LPM, ...)
Thanks Oliver, that was helpful. I will try now to do my testing using USB devices as it will likely be easier. Alejandra-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
