From: Dylan Hung <dylan_h...@aspeedtech.com>

[ Upstream commit 137d23cea1c044b2d4853ac71bc68126b25fdbb2 ]

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.

Fixes: 39bfab8844a0 ("net: ftgmac100: Add support for DT phy-handle property")
Signed-off-by: Dylan Hung <dylan_h...@aspeedtech.com>
Reviewed-by: Joel Stanley <j...@jms.id.au>
Signed-off-by: Jakub Kicinski <k...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/ethernet/faraday/ftgmac100.c |    5 +++++
 drivers/net/ethernet/faraday/ftgmac100.h |    8 ++++++++
 2 files changed, 13 insertions(+)

--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1817,6 +1817,11 @@ static int ftgmac100_probe(struct platfo
                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);
--- a/drivers/net/ethernet/faraday/ftgmac100.h
+++ b/drivers/net/ethernet/faraday/ftgmac100.h
@@ -170,6 +170,14 @@
 #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
  */
 #define FTGMAC100_PHYCR_MDC_CYCTHR_MASK        0x3f


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