lkml.org 
[lkml]   [2005]   [Jan]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: i8042 access timings
On Wed, 26 Jan 2005 12:05:47 -0500 (EST), linux-os
<linux-os@analogic.com> wrote:
> On Wed, 26 Jan 2005, 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?
> >
> > --
> > Dmitry
>
>
> The only time you need any delay at all is after you have send
...

Thank you Richard for this thorough explanation of IO access but I was
actually asking why we wanted to invert AUX data.

--
Dmitry
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:09    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site