+static void i2c_dump_register(struct mtk_i2c *i2c)
+{
+	dev_err(i2c->dev, "SLAVE_ADDR: 0x%x, INTR_MASK: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_SLAVE_ADDR),
+		mtk_i2c_readw(i2c, OFFSET_INTR_MASK));

I think this is too verbose and should be a debugging only patch not
really suited for upstream. But if you like it this way, then keep
the verbosity. However, dev_err is too strong, this really needs to be
dev_dbg. Timeouts can happen on an I2C bus, think about an EEPROM in a
long erase cycle while you want to read it. Perfectly normal.

 	if (ret == 0) {
-		dev_dbg(i2c->dev, "addr: %x, transfer timeout\n", msgs->addr);
+		dev_err(i2c->dev, "addr: %x, transfer timeout\n", msgs->addr);
+		i2c_dump_register(i2c);

Needs to stay dev_dbg as well.