On Tue, Apr 18, 2006 at 11:22:50AM +0530, Mandeep Sandhu wrote: > On 4/18/06, Greg KH <greg@xxxxxxxxx> wrote: > > On Tue, Apr 18, 2006 at 10:26:05AM +0530, Mandeep Sandhu wrote: > > > Hi all, > > > > > > How does one control the behavior of the LED's present on the various usb > > > flash drives. Is it controlled solely by software or is it like that > > > the usb host controller > > > controls the LED's operation. eg: when I write to my flash drive the > > > the LED blinks. > > > Is this done via some usb driver or does the usb host controller does > > > that for us > > > when we issue a write command to the drive? Is usbled.c under drivers/usb/misc > > > responsible for controlling this operation? Any pointers are welcome. > > > > No, there is no way to control it, it's up to the device itself. > > Well, Greg, the reason I was asking was because I wanted to know if the LED > of my drive could be switched off when I umount it. In windows I noticed that > the LED is switched off when the drive is ready to be unplugged. Is it that they > might be removing power to the drive? Could we acheive a similar result? Yes, Windows is removing power to that specific port. And yes, we can also do that if you want (unloading the whole USB host controller driver is overkill and not recommended, as it will prevent any other USB device from working in your machine.) See the archives of the linux-usb-devel and linux-pm mailing lists for a pointer to a program that lets you turn off the power for some USB hub ports (note that it will not work on all hardware.) good luck, greg k-h -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
