Re: [Qemu-devel] [PATCH] adb: change handler only when recognized

[Hervé Poussineau]

Le 12/03/2016 16:24, Mark Cave-Ayland a écrit :
> On 12/03/16 13:38, Hervé Poussineau wrote:
>
> > ADB devices must take new handler into account only when they recognize it.
> > This lets operating systems probe for valid/invalid handles, to know device 
> > capabilities.
> >
> > Add a FIXME in keyboard handler, which should use a different translation
> > table depending of the selected handler.
> >
> > Signed-off-by: Hervé Poussineau <address@hidden>
>
> Interesting. Can you explain a bit more about which OSs this patch
> affects and the symptoms it alleviates?

Here is a small list of handlers requested by some operating systems without 
the patch
HelenOS         kbd=1 mouse=2
MacOS 9         kbd=1 mouse=0xc (what is 0xc?)
Linux           kbd=3 mouse=4

Here is a small list of handlers requested by some operating systems with the 
patch
HelenOS         kbd=1 mouse=2
MacOS 9         kbd=1 mouse=2
Linux           kbd=3 mouse=2


I have no example of current problem with the keyboard part. However, I suspect 
it may be related some
problems John is seeing on some operating systems, as handler 1 and 2/3 must 
not use the same
translation table.
Note that MacOS 9 uses handler 1 (Apple Standard Keyboard), while Linux uses 
handler 3 (Apple Extended Keyboard LShift != RShift).

On mouse part, operating systems (like MacOS or Linux) try to probe the mouse 
model by testing
different handlers, and see which ones are accepted.
On Linux, the handler 1 and 2 have a 3 bytes protocol, while the handler 4 has 
a 4 bytes protocol.
Correctly supporting protocol 4 will be required to handle 3-button mice.

Hervé