uhci: rewrite UHCI emulator, fully async operation with multiple outstanding...
uhci: rewrite UHCI emulator, fully async operation with multiple outstanding transactions (Max Krasnyansky) This is esentially a re-write of the QEMU UHCI layer. My initial goal was to support fully async operation with multiple outstanding async transactions. Along the way I realized that I can greatly simplify and cleanup the overall logic. There was a lot of duplicate and confusing code in the UHCI data structure parsing and other places. We were actually violating UHCI spec in handling async ISOC transaction (host controller is not supposed to write into the frame pointer). The reason I wanted to support fully async operation is because current synchronous version is unusable with most devices exported from host (via usb-linux.c). Transactions take a long time and the whole VM becomes slow as hell. Current async support is very rudimentory and for the most part non-functional. Single transaction at a time is simply not enough. I have a device for which XP driver submits both IN and OUT packets at the same time. IN packet always times out unless OUT packet makes it to the device. Hence we must be able to process both in order for that device to work. The new code is backwards compatible and was first tested agains original synchronous usb-linux.c and builtin usb devices like tablet which is also synchronous. Rewrite of the usb-linux.c is coming up next. Async support was tested against various XP versions (ie XP, SP2, SP3) and a bunch of different USB devices: serial port controllers, mice, keyboard, JTAG dongles (from Xilinx and Altera). ISOC support was only lighly tested and needs more work. It's not any worse than current code though. UHCI parser changes are probably somewhat hard to review without the understanding of the UHCI spec. The async design should be fairly easy to follow. Basically we have a list of async objects for each pending transfer. Async objects are tagged with the original TD (transfer descriptor) address and token. We now support unlimited number of outstanding isoc and one outstanding bulk/intr/ctrl transfer per QH (queue head). UHCI spec does not have a clear protocol for the cancelation of the trasfer requests. Driver can yank out TDs on any frame boundary. In oder to handle that I added somewhat fancy TD validation logic logic to avoid unnecessary cancelations. Signed-off-by: NMax Krasnyansky <maxk@kernel.org> Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5050 c046a42c-6fe2-441c-8c8c-71466251a162
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