请问VPBE的Gamma Correction RAM Table 写不进去，为什么？

本帖最后由一只耳朵怪于 2018-6-22 10:47 编辑

各位专家大家好：
   我根据 VPBE UG 的4.5.5.7 Gamma Correction RAM Table 对RAM 进行如下操作:

static void davinci_enc_set_prgb(struct vid_enc_mode_info *mode_info)
[

   unsigned int pll_div6; //added by chengxiaoguang 11-09-19
u32 readpARM,ii;

................................................

////read gamma control register value ;
readparm = dispc_reg_in(VENC_GAMCTL);
printk("VENC_GAMCTL = %x n",readparm);

///////dispc_reg_out(VENC_RAMADR,0);
for(ii=0;ii<0x7F;ii++)
      [
   dispc_reg_out(VENC_RAMADR,ii);
            dispc_reg_out(VENC_RAMPORT,((ii<<9)|((ii<<1)+1)));

dispc_reg_out(VENC_RAMADR,0);
for(ii=0;ii<0x7F;ii++)
      [
   readparm=dispc_reg_in(VENC_RAMPORT);
      printk("%08x ",readparm);

.......................................................

dispc_reg_merge(VENC_GAMCTL,3 , 1);

发现读出来的值都是00，并且打开了gamma 矫正选项以后屏是黑的，请问哪里出了问题，谢谢。