[Qemu-devel] Re: [PATCH v2] add event queueing to USB HID

[Ian Jackson]

Paolo Bonzini writes ("[PATCH v2] add event queueing to USB HID"):
>         For v2 I changed the head/tail implementation of the FIFO buffer
>         (which was buggy when the queue became full) to head/count.
>         I then removed "have_data", which is the same as count>0
>         for pointer devices and the same as "changed" for keyboards.
>         This made event merging more correct than in Ian's code and
>         easier to understand than my v1.

Thanks.  Was my code buggy then ?  It's possible; the event merging
case is not easy to trigger in testing.

>         I left the "changed" member in USBHIDState, rather than moving it
>         to the keyboard, because it is useful to handle the idle period
>         (in USB_TOKEN_IN) in a device-independent way.  Without it the
>         code became more messy.

This leaves the same information recorded in the driver in two places
and is therefore IMO a bad idea.  I still think the way I did this is
best: have a common helper function used by the keyboard and pointer
code to deal with the idle handling.

Ian.