GRL_MIX_CTRL
regmap_read(hdmi->regs, GRL_MIX_CTRL, &val);
regmap_write(hdmi->regs, GRL_MIX_CTRL, val);
regmap_write(hdmi->regs, GRL_MIX_CTRL, val);
regmap_read(hdmi->regs, GRL_MIX_CTRL, &val);
regmap_write(hdmi->regs, GRL_MIX_CTRL, val);
regmap_set_bits(hdmi->regs, GRL_MIX_CTRL, MIX_CTRL_FLAT);