On Fri,  8 May 2020 19:13:38 +0200
Miquel Raynal [off-list ref] wrote:

+static int anfc_len_to_steps(struct nand_chip *chip, unsigned int len)
+{
+	unsigned int steps = 1, pktsize = len;
+
+	while (pktsize > ANFC_MAX_PKT_SIZE) {
+		steps *= 2;
+		pktsize = DIV_ROUND_UP(len, steps);
+	}

Same here, you shouldn't have a round_up() but instead complain if
"len != pkt_size * steps"

	if (len % 4)
		return -ENOTSUPP;

	if (len < ANFC_MAX_PKT_SIZE)
		return len;

	for (steps = 2; steps < ANFC_MAX_STEPS; steps *= 2) {
		pkt_size = len / steps;
		if (pkt_size <= ANFC_MAX_PKT_SIZE)
			break;
	}

	if (pkt_size * steps != len)
		return -ENOTSUPP;

	return pkt_size;

+
+	if (steps > ANFC_MAX_STEPS)
+		return -ENOTSUPP;
+
+	return steps;
+}