[SeaBIOS] questions about seabios ohci code

[Kevin O'Connor]

On Thu, Apr 15, 2010 at 10:40:21AM +0800, Qing Pei Wang wrote:
> Kevin,
>    i had tested the OHCI keyboard, the works

Great!  Please send the full SeaBIOS log.

>but not pretty good as enough.
> the reaction time is too long.

Is the time it takes a key to be shown too long?  Or are keys being
lost when typing fast?

> So i am trying to learn more about this things.
> BTW, seabios/OHCI use count=DIV_ROUND_UP(PIT_TICK_INTERVAL * 1000 * 2,
> PIT_TICK_RATE * ms)+1
> as the td count. i can not find any document  about that. Where can i find
> or some place i missing with OHCI spec?

That's internal to SeaBIOS.  SeaBIOS doesn't register a hardware irq
for usb, instead it polls for USB activity on every timer interrupt
(~55ms).  The above calculation determines how many key events to
queue so that no keyboard drops occur.  Usually a keyboard requests
service every 10ms, causing the above calculation will return 11 queue
items.

-Kevin