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

[moinejf@free.fr (Jean-Francois Moine)]

On Thu, 16 May 2013 20:26:18 +0100
Russell King <rmk+kernel@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@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)?

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