Hi!
> > Well with power it's simple: LCD is either powered or it's not. After
> > resuming the LCD should be always powered on, and the program can then
> > turn it back off if it's desired. FB blanking isn't a issue with X11/
> > Qtopia, as far as I understand? And finally, the 'user' requested power
> > state has to be tracked by the program that does the blanking (say an
> > audio player or such).
>
> So the user powers down the LCD, the FB blanking then blanks and
> unblanks. What should the current LCD power status be? The LCD should
> still be off as far as I can see yet the LCD/backlight class doesn't do
> this at present.
>
> I'm beginning to favour a system where backlight drivers only provide
> two functions:
>
> int (*set_status)(struct backlight_device *, int brightness, int power, int fb_blank);
> int (*get_status)(struct backlight_device *);
>
> set_status passes the user requested brightness and power values along
> with the current fb_blanking status to the driver. The driver can then
> set the hardware up as appropriate.
>
> get_status returns the brightness for the current configuration.
>
> The backlight core itself keeps track of the requested power and
> brightness values rather than having every backlight driver including
> the logic. This has the advantage of keeping behaviour the same and
> avoiding subtle logic bugs of which there are several at the moment.
>
> This also means that "echo 31 > brightness; cat brightness" will always
> give the expected answer of whatever brightness the user is requesting
> and the actual current driver brightness choice is available through
> "cat driver_brightness".
>
> Does this seem reasonable?
Yep. Keeping hardware drivers as simple as possible is good.
Pavel
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