net: vertexcom: mse102x: Simplify mse102x_rx_pkt_spi

The function mse102x_rx_pkt_spi is used in two cases:
* initial polling to re-arm RX interrupt
* level based RX interrupt handler

Both of them doesn't need an open-coded retry mechanism.
In the first case the function can be called again, if the return code
is IRQ_NONE. This keeps the error behavior during netdev open.

In the second case the proper retry would be handled implicit by
the SPI interrupt. So drop the retry code and simplify the receive path.

Signed-off-by: Stefan Wahren <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/vertexcom/mse102x.c

···
 	__be16 rx = 0;
 	u16 cmd_resp;
 	u8 *rxpkt;
-	int ret;
 
 	mse102x_tx_cmd_spi(mse, CMD_CTR);
-	ret = mse102x_rx_cmd_spi(mse, (u8 *)&rx);
-	cmd_resp = be16_to_cpu(rx);
-
-	if (ret || ((cmd_resp & CMD_MASK) != CMD_RTS)) {
+	if (mse102x_rx_cmd_spi(mse, (u8 *)&rx)) {
 		usleep_range(50, 100);
+		return IRQ_NONE;
+	}
 
-		mse102x_tx_cmd_spi(mse, CMD_CTR);
-		ret = mse102x_rx_cmd_spi(mse, (u8 *)&rx);
-		if (ret)
-			return IRQ_NONE;
-
-		cmd_resp = be16_to_cpu(rx);
-		if ((cmd_resp & CMD_MASK) != CMD_RTS) {
-			net_dbg_ratelimited("%s: Unexpected response (0x%04x)\n",
-					    __func__, cmd_resp);
-			mse->stats.invalid_rts++;
-			drop = true;
-			goto drop;
-		}
-
-		net_dbg_ratelimited("%s: Unexpected response to first CMD\n",
-				    __func__);
+	cmd_resp = be16_to_cpu(rx);
+	if ((cmd_resp & CMD_MASK) != CMD_RTS) {
+		net_dbg_ratelimited("%s: Unexpected response (0x%04x)\n",
+				    __func__, cmd_resp);
+		mse->stats.invalid_rts++;
+		drop = true;
+		goto drop;
 	}
 
 	rxlen = cmd_resp & LEN_MASK;
···
 	 * So poll for possible packet(s) to re-arm the interrupt.
 	 */
 	mutex_lock(&mses->lock);
-	mse102x_rx_pkt_spi(mse);
+	if (mse102x_rx_pkt_spi(mse) == IRQ_NONE)
+		mse102x_rx_pkt_spi(mse);
 	mutex_unlock(&mses->lock);
 
 	netif_dbg(mse, ifup, ndev, "network device up\n");