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    [W:0.022 / U:5.336 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site