[RFC 3/8] drm/i2c: nxp-tda998x: ensure VIP output mux is properly set

[Russell King - ARM Linux]

On Sat, May 18, 2013 at 08:56:59AM +0200, Jean-Francois Moine wrote:
> On Thu, 16 May 2013 20:26:18 +0100
> Russell King <rmk+kernel at arm.linux.org.uk> wrote:
> 
> > When switching between various drivers for this device, it's possible
> > that some critical registers are left containing values which affect
> > the device operation.  One such case encountered is the VIP output
> > mux register.  This defaults to 0x24 on powerup, but other drivers may
> > set this to 0x12.  This results in incorrect colours.
> > 
> > Fix this by ensuring that the register is always set to the power on
> > default setting.
> > 
> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> > ---
> >  drivers/gpu/drm/i2c/tda998x_drv.c |    3 +++
> >  1 files changed, 3 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
> > index d71c408..4b4db95 100644
> > --- a/drivers/gpu/drm/i2c/tda998x_drv.c
> > +++ b/drivers/gpu/drm/i2c/tda998x_drv.c
> > @@ -110,6 +110,7 @@ struct tda998x_priv {
> >  #define REG_VIP_CNTRL_5           REG(0x00, 0x25)     /* write */
> >  # define VIP_CNTRL_5_CKCASE       (1 << 0)
> >  # define VIP_CNTRL_5_SP_CNT(x)    (((x) & 3) << 1)
> > +#define REG_MUX_VP_VIP_OUT        REG(0x00, 0x27)     /* read/write */
> >  #define REG_MAT_CONTRL            REG(0x00, 0x80)     /* write */
> >  # define MAT_CONTRL_MAT_SC(x)     (((x) & 3) << 0)
> >  # define MAT_CONTRL_MAT_BP        (1 << 2)
> > @@ -438,6 +439,8 @@ tda998x_encoder_dpms(struct drm_encoder *encoder, int mode)
> >  
> >  	switch (mode) {
> >  	case DRM_MODE_DPMS_ON:
> > +		/* Write the default value MUX register */
> > +		reg_write(encoder, REG_MUX_VP_VIP_OUT, 0x24);
> >  		/* enable audio and video ports */
> >  		reg_write(encoder, REG_ENA_AP, 0xff);
> >  		reg_write(encoder, REG_ENA_VP_0, 0xff);
> 
> This register is never touched. Should not this setting better go at
> reset time (in tda998x_reset)?

Yes, you're right, it could be done there without any additional side
effects.  I've just moved it there.