On Wed, 2007-08-08 at 14:37 +0800, Zhang Rui wrote:
> On Mon, 2007-07-30 at 12:47 +0100, Richard Hughes wrote:
> > On 30/07/07, Matthew Garrett <[EMAIL PROTECTED]> wrote:
> > > On Sun, Jul 29, 2007 at 12:40:16PM -0400, Luming Yu wrote:
> > > >       switch (event) {
> > > >       case ACPI_VIDEO_NOTIFY_SWITCH:  /* User requested a switch,
> > > >                                        * most likely via hotkey. */
> > > >               acpi_bus_generate_event(device, event, 0);
> > > > +             keycode = KEY_UNKNOWN;
> > >
> > > KEY_SWITCHVIDEOMODE ?
> > 
> > Yes, please use this. This is what other ACPI drivers are using.
> > 
> > > What's wrong with the existing KEY_BRIGHTNESSDOWN and KEY_BRIGHTNESSUP?
> > 
> > Agree, this matches other drivers like thinkpad_acpi and sony-laptop.
> > 
> > > > +#define KEY_BRIGHTNESS_ZERO  0x1fd
> > > > +#define KEY_BRIGHTNESS_OFF   0x1fe
> > >
> > > You almost certainly want to go via linux-input if you're adding new
> > > keycodes.
> > 
> > Yup - do we have to distinguish between zero and off? Or is off
> > "switch panel backlight off" and zero is "switch to lowest brightness
> > level"?
> > 
> Hmm, I think they are slightly different.
> IMO, "zero" equals _BCM(0), it means to turn off the backlight, but we
> may still see the screen if there is a ambient light.
> "off" means turn off the output device, i.e. set to D1/D2/D3 state. 

Sure, so they are different states, but to a user they are both
effectively the same "screen is off". Is there any use case to removing
the backlight without powering down the display?

Richard.


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