Question about problem that color levels fall in the DM816x

Hi,

I'm using DM816x vpss Video driver, but when input the 1920x1080 YUV420(NV12) 100% color bar

from the decoder to the scaler, color levels fall after the  Display Controller. 

I show the YUV value before and after  Display Controller below.　

I want to mach the  YUV value before and after  Display Controller.

So,　I use vpss driver user guide as reference and check the settings of vpss driver and change nodes

from vcompmux:dvo2 to hdcompmux:dvo2.

After change nodes, problem that color levels fall became a little better, but YUV value before

and after  Display Controller do not match. 

I show the YUV value before and after  Display Controller when change nodes

from vcompmux:dvo2 to hdcompmux:dvo2 below.

After that I found that hdcomp has Following some CSC mode and change this mode

by changing source of dctrl.c.

But, in case of the default mode(VPS_CSC_MODE_HDTV_GRAPHICS_Y2R) , YUV value before

and after  Display Controller was the most close.

enum vps_cscmode {
VPS_CSC_MODE_SDTV_VIDEO_R2Y = 0,
/**< Select coefficient for SDTV Video */
VPS_CSC_MODE_SDTV_VIDEO_Y2R,
/**< Select coefficient for SDTV Video */
VPS_CSC_MODE_SDTV_GRAPHICS_R2Y,
/**< Select coefficient for SDTV Graphics */
VPS_CSC_MODE_SDTV_GRAPHICS_Y2R,
/**< Select coefficient for SDTV Graphics */
VPS_CSC_MODE_HDTV_VIDEO_R2Y,
/**< Select coefficient for HDTV Video */
VPS_CSC_MODE_HDTV_VIDEO_Y2R,
/**< Select coefficient for HDTV Video */
VPS_CSC_MODE_HDTV_GRAPHICS_R2Y,
/**< Select coefficient for HDTV Graphics */
VPS_CSC_MODE_HDTV_GRAPHICS_Y2R,
/**< Select coefficient for HDTV Graphics */
VPS_CSC_MODE_MAX,
/**< Should be the last value of this enumeration.
Will be used by driver for validating the input parameters. */
VPS_CSC_MODE_NONE = 0xFFFFu
/**< Used when coefficients are provided */
};

Also, I tried to change the Following parameters of the CPROC in vcomp in user settings,

but can not match  YUV value before and after Display Controller.

struct vps_cprocciecamcfg {
u32 multcoeff[VPS_CPROC_NUM_COEFF][VPS_CPROC_NUM_COEFF];
/**< Multiplication coefficients in the format
A0, B0, C0 in the first row,
A1, B1, C1 in the second row,
and A2, B2, C2 in the third row. */
u32 s, t, a, cz;

u32 gy, gub, guy, gvg, vgr;
} ;

struct vps_cprocuciecamcfg {
u32 multcoeff[VPS_CPROC_NUM_COEFF][VPS_CPROC_NUM_COEFF];
/**< Multiplication coefficients in the format
A0, B0, C0 in the first row,
A1, B1, C1 in the second row,
and A2, B2, C2 in the third row. */
u32 a, cz, s, x0;
} ;

So,Could you tell me CPROC of parameters, such as YUV value before and after Display Controller match,

or, something else a solution?

Thanks,

fumiya tanaka