si21_writereg
return si21_writereg(state, buf[0], buf[1]);
if (si21_writereg(state, LNB_CTRL_REG_1,
if (si21_writereg(state, LNB_CTRL_REG_1, val))
return si21_writereg(state, LNB_CTRL_REG_1, val | 0x20);
return si21_writereg(state, LNB_CTRL_REG_1, (val & ~0x20));
return si21_writereg(state, LNB_CTRL_REG_1, val | 0x40);
return si21_writereg(state, LNB_CTRL_REG_1, (val & ~0x40));
si21_writereg(state, SYSTEM_MODE_REG, id | 0x40); /* standby off */