net: ti: icssg-prueth: Adjust the number of TX channels for SR1.0

As SR1.0 uses the current higher priority channel to send commands to
the firmware, take this into account when setting/getting the number
of channels to/from the user.

Based on the work of Roger Quadros in TI's 5.10 SDK [1].

[1]: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/?h=ti-linux-5.10.yCo-developed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Diogo Ivo <diogo.ivo@siemens.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: MD Danish Anwar <danishanwar@ti.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/ti/icssg/icssg_ethtool.c

@@ -142,6 +142,9 @@ static int emac_set_channels(struct net_device *ndev,
 
 	emac->tx_ch_num = ch->tx_count;
 
+	if (emac->is_sr1)
+		emac->tx_ch_num++;
+
 	return 0;
 }
 
@@ -152,8 +155,17 @@ static void emac_get_channels(struct net_device *ndev,
 
 	ch->max_rx = 1;
 	ch->max_tx = PRUETH_MAX_TX_QUEUES;
+
+	/* Disable multiple TX channels due to timeouts
+	 * when using more than one queue */
+	if (emac->is_sr1)
+		ch->max_tx = 1;
+
 	ch->rx_count = 1;
 	ch->tx_count = emac->tx_ch_num;
+
+	if (emac->is_sr1)
+		ch->tx_count--;
 }
 
 static const struct ethtool_rmon_hist_range emac_rmon_ranges[] = {