net: ethernet: ti: am65-cpsw-nuss: cleanup DMA Channels before using them

The TX and RX DMA Channels used by the driver to exchange data with CPSW
are not guaranteed to be in a clean state during driver initialization.
The Bootloader could have used the same DMA Channels without cleaning them
up in the event of failure. Thus, reset and disable the DMA Channels to
ensure that they are in a clean state before using them.

Fixes: 93a76530 ("net: ethernet: ti: introduce am65x/j721e gigabit eth subsystem driver")
Reported-by: Schuyler Patton <spatton@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20240417095425.2253876-1-s-vadapalli@ti.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -2793,6 +2793,8 @@ static void am65_cpsw_unregister_devlink(struct am65_cpsw_common *common)
 
 static int am65_cpsw_nuss_register_ndevs(struct am65_cpsw_common *common)
 {
+	struct am65_cpsw_rx_chn *rx_chan = &common->rx_chns;
+	struct am65_cpsw_tx_chn *tx_chan = common->tx_chns;
 	struct device *dev = common->dev;
 	struct am65_cpsw_port *port;
 	int ret = 0, i;
@@ -2805,6 +2807,22 @@ static int am65_cpsw_nuss_register_ndevs(struct am65_cpsw_common *common)
 	if (ret)
 		return ret;
 
+	/* The DMA Channels are not guaranteed to be in a clean state.
+	 * Reset and disable them to ensure that they are back to the
+	 * clean state and ready to be used.
+	 */
+	for (i = 0; i < common->tx_ch_num; i++) {
+		k3_udma_glue_reset_tx_chn(tx_chan[i].tx_chn, &tx_chan[i],
+					  am65_cpsw_nuss_tx_cleanup);
+		k3_udma_glue_disable_tx_chn(tx_chan[i].tx_chn);
+	}
+
+	for (i = 0; i < AM65_CPSW_MAX_RX_FLOWS; i++)
+		k3_udma_glue_reset_rx_chn(rx_chan->rx_chn, i, rx_chan,
+					  am65_cpsw_nuss_rx_cleanup, !!i);
+
+	k3_udma_glue_disable_rx_chn(rx_chan->rx_chn);
+
 	ret = am65_cpsw_nuss_register_devlink(common);
 	if (ret)
 		return ret;