At the current stage, the USB HID and storage drivers are prinicpally
working but not stable. If interrupts are not processed fast enough,
devices will get sporadically disconnected.
The USB host-controller driver is not part of the normal Linux kernel.
For this reason, we need to download it separately. There exists a
'prepare_rpi' rule in the 'dde_linux/Makefile' to automate this process.
This fixes issues with several HID keyboards by implementing
get_unaligned_le16(), which obviously may also fix other not-yet-known
issues. Hint: I had to look out for suspicious lines like follows in the
verbose log.
[init -> usb_drv] get_unaligned_le16 called, not implemented
Also, quirks for cherry keyboards are now applied.
The new 'dde_linux' repository will host device drivers ported from the
Linux kernel. In contrast to the original 'linux_drivers' repository,
'dde_linux' does not contain any 3rd-party source code. To download the
Linux kernel source code and extract the drivers, execute the 'make
prepare' rule of the top-level Makefile. The initial version of the
'dde_linux' repository comes with an USB driver. The porting methodology
follows the path of the Intel GEM port. Instead of attempting to provide
a generic Linux environment that works across drivers, each driver comes
with a specially tailored DDE.
The DDE consists of Genode-specific implementations of Linux API
functions as declared in 'lx_emul.h'. Most of these functions are
dummies that must merely be provided to resolve dependencies at the
linking stage. They are called by unused code-paths.
As of now, the USB driver support UHCI, EHCI on the x86_32 platform. I
exposes USB HID devices and USB storage devices via Genode's input-session
and block-session respectively.
The USB driver is accompanied with two run scripts 'run/usb_hid.run' and
'run/usb_storage.run'.
