realtek: eth: cleanup hardware transmit handling

There is a workaround in the transmit path for the RTL838x SoCs. This
is basically an open coded read_poll_timeout() and makes the code hard
to read. Additionally the magic trigger calculation is not easy to
understand.

Simplify things by using kernel standards and a better macro.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/22217
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
index 94f7db58d91c9b80d4e18b15a6702f45d8b58d1e..c68940e346d8f9f29ce6f3c5a1dec7016e44abfd 100644 (file)
--- a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
+++ b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
@@ -24,12 +24,12 @@
 #include <asm/mach-rtl-otto/mach-rtl-otto.h>
 #include "rtl838x_eth.h"
 
-#define RTETH_OWN_CPU          1
-#define RTETH_RX_RING_SIZE     128
-#define RTETH_RX_RINGS         2
-#define RTETH_TX_RING_SIZE     16
-#define RTETH_TX_RINGS         2
-#define RTETH_TX_TRIGGER       0x16
+#define RTETH_OWN_CPU                  1
+#define RTETH_RX_RING_SIZE             128
+#define RTETH_RX_RINGS                 2
+#define RTETH_TX_RING_SIZE             16
+#define RTETH_TX_RINGS                 2
+#define RTETH_TX_TRIGGER(ctrl, ring)   ((0x16 >> ring) & ctrl->r->tx_trigger_mask)
 
 #define NOTIFY_EVENTS  10
 #define NOTIFY_BLOCKS  10
@@ -925,7 +925,7 @@ static void rteth_tx_timeout(struct net_device *ndev, unsigned int txqueue)
 static int rteth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
        struct rteth_ctrl *ctrl = netdev_priv(netdev);
-       int slot, len = skb->len, dest_port = -1;
+       int val, slot, len = skb->len, dest_port = -1;
        int ring = skb_get_queue_mapping(skb);
        struct device *dev = &ctrl->pdev->dev;
        struct rteth_packet *packet;
@@ -990,18 +990,16 @@ static int rteth_start_xmit(struct sk_buff *skb, struct net_device *netdev)
 
        spin_lock(&ctrl->tx_lock);
 
-       /* Before starting TX, prevent a Lexra bus bug on RTL8380 SoCs */
-       if (ctrl->r->family_id == RTL8380_FAMILY_ID) {
-               for (int i = 0; i < 10; i++) {
-                       u32 val = sw_r32(ctrl->r->dma_if_ctrl);
-                       if ((val & ctrl->r->tx_rx_enable) == ctrl->r->tx_rx_enable)
-                               break;
-               }
-       }
+       /*
+        * Issue send for 1 or 2 triggers. On some SoCs (especially RTL838x) there is a known
+        * bug, where the hardware sometimes reads empty values from the register. Work around
+        * that with a poll that checks if TX/RX is enabled in the register.
+        */
+       if (read_poll_timeout(sw_r32, val, val & ctrl->r->tx_rx_enable,
+                            0, 5000, false, ctrl->r->dma_if_ctrl))
+               dev_warn_once(dev, "DMA interface ctrl register read failed\n");
 
-       /* issue SoC independent send for 1 or 2 triggers with some bit vodoo */
-       sw_w32_mask(0, (RTETH_TX_TRIGGER >> ring) & ctrl->r->tx_trigger_mask,
-                   ctrl->r->dma_if_ctrl);
+       sw_w32(val | RTETH_TX_TRIGGER(ctrl, ring), ctrl->r->dma_if_ctrl);
 
        netdev->stats.tx_packets++;
        netdev->stats.tx_bytes += len;