[lkml]   [2003]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: keyboard - was: Re: Linux 2.6.0-test4
    > > Are you saying that it isn't possible for i8042.c to simply pass all
    > > events (including duplicates) to the keyboard driver to sanitise?
    > I am saying that I would like nothing better than that.
    > But it is a fundamental change of setup.

    Well... I think the overall design is the right one. The atkbd driver
    expects to be talking to an AT keyboard, usually using Set 2.

    However, the bytes that come from the i8042 are a mixture of Set 1 and
    Set 2. Set 1 because the key releases have their 8th bits set, and Set
    2 because we get the non-XT keys escaped with E0. I guess the keyboard
    is sending Set 2 and the BIOS is translating the set 2 codes to set 1
    for "compatibility with XT software".

    So the i8042 layer is IMHO the right place to untranslate this mess back
    into normal Set 2. The problem is that the BIOS translation is not
    invertible, so we have to hack the untranslation as best we can. The
    current algorithm is to untranslate all bytes 0x00-0x7f, and to
    untranslate the others only if there was a previous key press. This
    means the i8042 layer has to know about scancodes, knowledge which
    probably only belongs in the atkbd layer.

    Probably, now that I think about it, the sanitization of duplicate key
    releases should rightfully be part of the atkbd layer, because those
    codes are actually being sent from the keyboard.

    But either way, the problem remains to find a good untranslate
    hack^Walgorithm. Because we are getting duplicate key releases, we have
    to make sure they they are either untranslated or removed. Sending them
    through unchanged, as we were in -test1 causes lots of grief to the
    atkbd layer.

    At this late stage, I don't think it is a good idea to completely
    rewrite the untranslate algorithm. So we continue to hack it and hack
    it until it works. :-/


    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:48    [W:0.021 / U:12.740 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site