Alan Stern wrote:
On Thu, 10 Sep 2009, Gabriel Rossetti wrote:
Hello everyone,
From my thread on the libusb mailing list
(http://www.nabble.com/Does-libusb-1.0-get-it%27s-devices-stolen-by-the-OS%27s-native-driver--td25367199.html),
I came to understand that the linux version of the HID driver is unable
to send data to the device.
This is of course completely untrue. If the HID driver were unable to
send data to devices, how could it turn the NumLock and CapsLock LEDs
in USB keyboards on and off?
From what I read on the
HID spec (http://www.usb.org/developers/devclass_docs/HID1_11.pdf) it
says that a report can define input and output (section 6.2.2.5, page
29). Is this correct, that the linux HID driver only partially
implements the HID spec and that the driver won't let me send arbitrary
(non-keyboard led on/off) data to a HID device?
It is true that devices can have both input and output reports. It is
not true that the Linux HID driver fails to implement output reports or
that it prevents you from sending data to HID devices.
If so, from what I
understand, I have two choices :
1) write a kernel driver for my device (which is why I made it to be HID
compliant in the first place, to not have to write a driver for linux,
mac & windows)
2) use a userland lib like libusb/libhid and have to deal with the
kernel's HID driver claiming the device
Are there any other choices? Did I miss something?
You should ask the HID developers rather than the USB developers. See
the entries for HID CORE LAYER and USB HID/HIDBP DRIVERS in the kernel
source file MAINTAINERS.
Alan Stern
Thank you for those clarifications, I was unaware that this list was not
the correct one.
Gabriel
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