+	/* Read and configure the IMASK0 register for unmasking the interrupts */
+	ret = oa_tc6_perform_ctrl(tc6, IMASK0, &regval, 1, false, false);
+	if (ret)
+		return ret;

Can you use oa_tc6_read_register() here? I guess the question is, what
does tc6->protect default to until it is set later in this function?
So long as it defaults to false, i guess you can use the register
read/write functions, which are a lot more readable than this generic
oa_tc6_perform_ctrl().

+
+	regval &= ~(TXPEM & TXBOEM & TXBUEM & RXBOEM & LOFEM & HDREM);
+
+	ret = oa_tc6_perform_ctrl(tc6, IMASK0, &regval, 1, true, false);
+	if (ret)
+		return ret;
+
+	/* Read STDCAP register to get the MAC-PHY standard capabilities */
+	ret = oa_tc6_perform_ctrl(tc6, STDCAP, &regval, 1, false, false);
+	if (ret)
+		return ret;
+
+	mincps = FIELD_GET(MINCPS, regval);
+	ctc = (regval & CTC) ? true : false;
+
+	regval = 0;
+	oa_node = of_get_child_by_name(spi->dev.of_node, "oa-tc6");
+	if (oa_node) {
+		/* Read OA parameters from DT */
+		if (of_property_present(oa_node, "oa-cps")) {
+			ret = of_property_read_u32(oa_node, "oa-cps", &tc6->cps);

If of_property_read_u32() does not find the property, it is documented
to not touch tc6->cps. So you can set tc6->cps to the default 64,
before the big if, and skip the of_property_present(). You can then
probably remove the else at the end as well.

+			if (ret < 0)
+				return ret;
+			/* Return error if the configured cps is less than the
+			 * minimum cps supported by the MAC-PHY.
+			 */
+			if (tc6->cps < mincps)
+				return -ENODEV;

A dev_err() would be nice here to indicate why.

+		} else {
+			tc6->cps = 64;
+		}
+		if (of_property_present(oa_node, "oa-txcte")) {
+			/* Return error if the tx cut through mode is configured
+			 * but it is not supported by MAC-PHY.
+			 */
+			if (ctc)
+				regval |= TXCTE;
+			else
+				return -ENODEV;

and a dev_err() here as well.

+		}
+		if (of_property_present(oa_node, "oa-rxcte")) {
+			/* Return error if the rx cut through mode is configured
+			 * but it is not supported by MAC-PHY.
+			 */
+			if (ctc)
+				regval |= RXCTE;
+			else
+				return -ENODEV;
+		}

and another dev_err(). Without these prints, you probably need to
modify the code to figure out why the probe failed.

Was there a reason to have prote initially, and then remove it here?

    Andrew