[PATCH] ARM: mxs/tx28: fix up LCD pads

[Shawn Guo]

On Fri, Mar 11, 2011 at 05:16:18PM +0100, Lothar Waßmann wrote:
> Hi,
> 
> Shawn Guo writes:
> > * In any case, LCD only needs one group of VSYNC, HSYNC, and DOTCLK.
> >   So remove the redundant and useless one.
> > * LCD_ENABLE pad should not work as a GPIO for LCD, and there must be
> >   one pad for ENABLE function.
> > 
> > Signed-off-by: Shawn Guo <shawn.guo at freescale.com>
> > ---
> > Hi Lothar, Uwe,
> > 
> > I do not have the schematics of TX28 board, and I'm guessing the fix.
> > So it really needs your comments here.
> > 
> > Regards,
> > Shawn
> > 
> >  arch/arm/mach-mxs/mach-tx28.c |    6 +-----
> >  1 files changed, 1 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/arm/mach-mxs/mach-tx28.c b/arch/arm/mach-mxs/mach-tx28.c
> > index b65e371..16a0059 100644
> > --- a/arch/arm/mach-mxs/mach-tx28.c
> > +++ b/arch/arm/mach-mxs/mach-tx28.c
> > @@ -61,11 +61,7 @@ static const iomux_cfg_t tx28_stk5v3_pads[] __initconst = {
> >  	MX28_PAD_LCD_RD_E__LCD_VSYNC | LCD_MODE,
> >  	MX28_PAD_LCD_WR_RWN__LCD_HSYNC | LCD_MODE,
> >  	MX28_PAD_LCD_RS__LCD_DOTCLK | LCD_MODE,
> > -	MX28_PAD_LCD_CS__LCD_CS | LCD_MODE,
> >
> This one is correct as it stands (i.e. the suggested change is wrong).
> 
So your panel is using LCD_CS without using LCD_RS as a couple?

> > -	MX28_PAD_LCD_VSYNC__LCD_VSYNC | LCD_MODE,
> > -	MX28_PAD_LCD_HSYNC__LCD_HSYNC | LCD_MODE,
> > -	MX28_PAD_LCD_DOTCLK__LCD_DOTCLK | LCD_MODE,
> >
> These should be removed from the pin list, as suggested.
> 
> > -	MX28_PAD_LCD_ENABLE__GPIO_1_31 | LCD_MODE,
> > +	MX28_PAD_LCD_CS__LCD_ENABLE | LCD_MODE,
> >
> This change is also wrong. The pad is used as a (power) enable pin for
> a certain family of LCDs that we recommend for use with our
> modules. It should be configured as GPIO and pulled high/low whenever
> the LCD is activated/deactivated (just like the LCD_RESET pad below).
> 
This pad is not designed for a power enable pin but DATA_ENABLE
signal.  Why does your panel need two power enable pins here, LCD_CS
and LCD_RESET?

> >  	MX28_PAD_LCD_RESET__GPIO_3_30 | LCD_MODE,
> >  	MX28_PAD_PWM0__PWM_0 | LCD_MODE,
> >  

-- 
Regards,
Shawn