Re: [RFT/PATCH] i8042: remove polling timer (v6)

[Dmitry Torokhov <dtor@insightbb.com>]

On Sunday 29 October 2006 18:20, Dave Neuer wrote:
> On 8/23/06, Dmitry Torokhov <dtor@insightbb.com> wrote:
> > Hi everyone,
> >
> > Here is another version of the patch removing polling timer from i8042
> > which is needed if we want tickless kernel. Keyboards should now work
> > on boxes that do not have mouse plugged in. PLease give it a test.
> 
>  What's the intent of this; just to allow tickless? Or is it also to
> make the i8042 driver less racy? I ask because I've applied this over
> (a modified) 2.6.18 on my Compaq Presario X1010us laptop which has
> been driving me crazy w/ Synaptics problems and keyboard problems
> (intermittent, but   frequent enough lately that I finally figured I
> needed to do something about it).
> 
> If removing raciness is part of the goal, isn't the window in
> i8042_aux_write still a problem?
> 
> 	if (port->mux == -1)
> 		retval = i8042_command(&c, I8042_CMD_AUX_SEND);
> 	else
> 		retval = i8042_command(&c, I8042_CMD_MUX_SEND + port->mux);
> 
>         /* i8042_command has re-enabled interrupts;
>            what happens if real interrupt happens here, before we call
> the ISR ourselves? */
> 
> 	i8042_interrupt(0, NULL, NULL);
> 	return retval;
> }
>

Hi Dave,

i8042_interrupt() uses spinlock to serialize access to the KBC so if real
interrupt happens before we call i8042_interrupt() manually (and it should
normally happen) it will just process the response and second i8042_interrupt()
will be just a no-op.

Sorry, freel like crap, will try re-reading and responding to the rest of
your email later...
 
-- 
Dmitry
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