On 4/18/06, Sharath <sharath_75@xxxxxxxxx> wrote: > Hi Mandeep, > > ----- Original Message ---- > From: Mandeep Sandhu <mandeep.stinger@xxxxxxxxx> > To: kernelnewbies <kernelnewbies@xxxxxxxxxxxx> > Sent: Tuesday, April 18, 2006 3:52:50 PM > Subject: Re: controlling LED's on USB flash drives > > 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? > > This would depend on the electronics of the drive however, the LED status is set by the controller on the USB device. This status is commnunicated to it by the UBS protocol. Whena device is inserted, there are softwrae drivers that control the device and later it is mount onto a location in the filesystem. > > The two drivers for the hardware are: > ehci_hcd > uhci_hcd You're correct. Removing ehci_hcd switched off the LED. I guess removing this module must be powering off the device. I'll look into the cleanup code to confirm this. Thanks. > > So in order to make the light go away try unmounting the drive and then rmmod-ing the above modules. The LED should turn off. Now you can unplug the device. > > However, these modules also detect the insertion of a device hence you would need to reenable them by inserting (insmod). also the rmmod and insmod can only be run as a priviledged user. > > Yes you can incorporate a buoon on the desktop the does that inserts and removes these modules.. but again need to run as priviledged user. > > -Sharath > > > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
