[PATCH 1/1] net: ftgmac100: Fix Aspeed ast2600 TX hang issue

[Dylan Hung]

The new HW arbitration feature on Aspeed ast2600 will cause MAC TX to
hang when handling scatter-gather DMA.  Disable the problematic feature
by setting MAC register 0x58 bit28 and bit27.

Signed-off-by: Dylan Hung <dylan_h...@aspeedtech.com>
---
 drivers/net/ethernet/faraday/ftgmac100.c | 5 +++++
 drivers/net/ethernet/faraday/ftgmac100.h | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c 
b/drivers/net/ethernet/faraday/ftgmac100.c
index 87236206366f..00024dd41147 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1817,6 +1817,11 @@ static int ftgmac100_probe(struct platform_device *pdev)
                priv->rxdes0_edorr_mask = BIT(30);
                priv->txdes0_edotr_mask = BIT(30);
                priv->is_aspeed = true;
+               /* Disable ast2600 problematic HW arbitration */
+               if (of_device_is_compatible(np, "aspeed,ast2600-mac")) {
+                       iowrite32(FTGMAC100_TM_DEFAULT,
+                                 priv->base + FTGMAC100_OFFSET_TM);
+               }
        } else {
                priv->rxdes0_edorr_mask = BIT(15);
                priv->txdes0_edotr_mask = BIT(15);
diff --git a/drivers/net/ethernet/faraday/ftgmac100.h 
b/drivers/net/ethernet/faraday/ftgmac100.h
index e5876a3fda91..63b3e02fab16 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.h
+++ b/drivers/net/ethernet/faraday/ftgmac100.h
@@ -169,6 +169,14 @@
 #define FTGMAC100_MACCR_FAST_MODE      (1 << 19)
 #define FTGMAC100_MACCR_SW_RST         (1 << 31)
 
+/*
+ * test mode control register
+ */
+#define FTGMAC100_TM_RQ_TX_VALID_DIS (1 << 28)
+#define FTGMAC100_TM_RQ_RR_IDLE_PREV (1 << 27)
+#define FTGMAC100_TM_DEFAULT                                                   
\
+       (FTGMAC100_TM_RQ_TX_VALID_DIS | FTGMAC100_TM_RQ_RR_IDLE_PREV)
+
 /*
  * PHY control register
  */
-- 
2.17.1