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    SubjectRe: 2.6.38-rc3-git1: Reported regressions 2.6.36 -> 2.6.37
    On Thu, Feb 3, 2011 at 4:06 PM, Dave Airlie <> wrote:
    > If we are setting a mode on a connector it automatically will end up
    > in a DPMS on state,
    > so this seemed correct from what I can see.

    The more I look at that function, the more I disagree with you and
    with that patch.

    The code is just crazy.

    First off, it isn't even necessarily setting a mode to begin with,
    because as far as I can tell. If the mode doesn't change, neither
    mode_changed nor fb_changed will be true, afaik. There seems to be a
    fair amount of code there explicitly to avoid changing modes if not

    But even _if_ we are setting a mode, if I read the code correctly, the
    mode may be set to NULL - which seems to mean "turn it off". In which
    case it looks to me that drm_helper_disable_unused_functions() will
    actually do a

    (*crtc_funcs->dpms)(crtc, DRM_MODE_DPMS_OFF);

    call on the crtc in question. So then blindly just saying "it's mode
    DRM_MODE_DPMS_ON" afterwards looks rather bogus to me.

    _Maybe_ it would work if it was done before that whole
    "disable_unused" logic. Or maybe it should just be done in
    drm_crtc_helper_set_mode(), which is what actually sets the mode (but
    there's the 'fb_changed' case too)

    > A future mode set shouldn't ever not turn the connector on, since
    > modesetting is an implicit
    > DPMS,
    > It sounds like something more subtle than that, though I'm happy to
    > revert this for now, and let Keith
    > think about it a bit more.

    So I haven't heard anything from Keith. Keith? Just revert it? Or do
    you have a patch for people to try?


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