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SubjectRe: i8042 access timings
On Wed, Jan 26, 2005 at 11:36:41AM -0500, Dmitry Torokhov wrote:
> On Wed, 26 Jan 2005 16:43:07 +0100, Vojtech Pavlik <vojtech@suse.cz> wrote:
> > On Tue, Jan 25, 2005 at 02:41:14AM -0500, Dmitry Torokhov wrote:
> > > @@ -213,7 +217,10 @@
> > > if (!retval)
> > > for (i = 0; i < ((command >> 8) & 0xf); i++) {
> > > if ((retval = i8042_wait_read())) break;
> > > - if (i8042_read_status() & I8042_STR_AUXDATA)
> > > + udelay(I8042_STR_DELAY);
> > > + str = i8042_read_status();
> > []
> > > + udelay(I8042_DATA_DELAY);
> > > + if (str & I8042_STR_AUXDATA)
> > > param[i] = ~i8042_read_data();
> > > else
> > > param[i] = i8042_read_data();
> >
> > We may as well drop the negation. It's a bad way to signal the data came
> > from the AUX port. Then we don't need the extra status read and can just
> > proceed to read the data, since IMO we don't need to wait inbetween,
> > even according to the IBM spec.
>
> Do you remember why it has been done to begin with?

Yes. It's only for the detection of the AUX port. I wanted to know
whether the byte we receive in the AUX_LOOP command really comes back
through the AUX interface and not through the KBD interface. Since there
isn't any other information path for signalling which interface
i8042_command() received the byte through, I just negated the value
there.

--
Vojtech Pavlik
SuSE Labs, SuSE CR
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