Subject: [PATCH 2/2] backlight: Fix blanking for L4F00242T03 LCD

From: [email-masked] (Alberto Panizzo)
Date: Sat, 05 Jun 2010 11:22:02 +0200

On sab, 2010-06-05 at 03:25 +0200, Marek Vasut wrote:
> Dne P? 4. ?ervna 2010 09:29:43 Alberto Panizzo napsal(a):
> > On ven, 2010-06-04 at 07:52 +0200, Marek Vasut wrote:
> > > The LCD was turned on if the variable power was > 0, but that was
> > > incorrect. The LCD has to be turned on in every case but POWERDOWN.
> > > 
> > > Signed-off-by: Marek Vasut <[email-masked]>
> > 
> > Ack
> > 
> > > ---
> > > 
> > >  drivers/video/backlight/l4f00242t03.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/drivers/video/backlight/l4f00242t03.c
> > > b/drivers/video/backlight/l4f00242t03.c index 9093ef0..ac20b2e 100644
> > > --- a/drivers/video/backlight/l4f00242t03.c
> > > +++ b/drivers/video/backlight/l4f00242t03.c
> > > @@ -78,7 +78,7 @@ static int l4f00242t03_lcd_power_set(struct lcd_device
> > > *ld, int power)
> > > 
> > >  	const u16 slpin = 0x10;
> > >  	const u16 disoff = 0x28;
> > > 
> > > -	if (power) {
> > > +	if (power < FB_BLANK_POWERDOWN) {
> > > 
> > >  		if (priv->lcd_on)
> > >  		
> > >  			return 0;
> > 
> > lcd.h states:
> > struct lcd_ops {
> > 	/* Get the LCD panel power status (0: full on, 1..3: controller
> > 	   power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
> > 	int (*get_power)(struct lcd_device *);
> > 	/* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) 
> */
> > 	int (*set_power)(struct lcd_device *, int power);
> > 
> > AFAIK the gray area between FB_BLANK_NORMAL and FB_BLANK_HSYNC_SUSPEND
> > can be chosen as needs.
> > 
> > Why not:
> > 
> > + #define POWER_IS_ON(pwr)	((pwr) <= FB_BLANK_NORMAL)
> > 
> > ...
> > 
> > -	if (power) {
> > +	if (POWER_IS_ON(power)) {
> >  		if (priv->lcd_on)
> >  			return 0;
> > 
> > So with FB_BLANK_NORMAL the lcd is active and on -> low latencies
> > in re-enabling the video out, but for !POWER_IS_ON(power) we will send
> > the lcd to standby.
> > 
> > It have to be implemented for power == FB_BLANK_POWERDOWN to turn off the
> > regulators of the lcd.
> > 
> > What do you think about?
> 
> Thanks! I sent a new (better) version. If you want credit in it, tell me how 
> should I add you one ;-)

Oh no, you have the credit on it. I admit that my L4F00242T03 is not my 
best driver, but soon I will work on it again ;)

Thank you for your fix!

Regards,

-- 
Alberto!

        Be Persistent!
                - Greg Kroah-Hartman (FOSDEM 2010)