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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dylan Hung <dylan_hung@aspeedtech.com>,
        Joel Stanley <joel@jms.id.au>, Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 5.9 040/757] net: ftgmac100: Fix Aspeed ast2600 TX hang issue
Date:   Tue, 27 Oct 2020 14:44:50 +0100
Message-Id: <20201027135452.402824267@linuxfoundation.org>
In-Reply-To: <20201027135450.497324313@linuxfoundation.org>
References: <20201027135450.497324313@linuxfoundation.org>
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From: Dylan Hung <dylan_hung@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_hung@aspeedtech.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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