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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
        "Finn Thain" <fthain@telegraphics.com.au>,
        "Stan Johnson" <userm57@yahoo.com>,
        "David S. Miller" <davem@davemloft.net>
Date:   Fri, 24 Apr 2020 00:07:13 +0100
Message-ID: <lsq.1587683028.429395064@decadent.org.uk>
Subject: [PATCH 3.16 206/245] net/sonic: Quiesce SONIC before
 re-initializing descriptor memory
In-Reply-To: <lsq.1587683027.831233700@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Finn Thain <fthain@telegraphics.com.au>

commit 3f4b7e6a2be982fd8820a2b54d46dd9c351db899 upstream.

Make sure the SONIC's DMA engine is idle before altering the transmit
and receive descriptors. Add a helper for this as it will be needed
again.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/net/ethernet/natsemi/sonic.c | 25 +++++++++++++++++++++++++
 drivers/net/ethernet/natsemi/sonic.h |  3 +++
 2 files changed, 28 insertions(+)

--- a/drivers/net/ethernet/natsemi/sonic.c
+++ b/drivers/net/ethernet/natsemi/sonic.c
@@ -103,6 +103,24 @@ static int sonic_open(struct net_device
 	return 0;
 }
 
+/* Wait for the SONIC to become idle. */
+static void sonic_quiesce(struct net_device *dev, u16 mask)
+{
+	struct sonic_local * __maybe_unused lp = netdev_priv(dev);
+	int i;
+	u16 bits;
+
+	for (i = 0; i < 1000; ++i) {
+		bits = SONIC_READ(SONIC_CMD) & mask;
+		if (!bits)
+			return;
+		if (irqs_disabled() || in_interrupt())
+			udelay(20);
+		else
+			usleep_range(100, 200);
+	}
+	WARN_ONCE(1, "command deadline expired! 0x%04x\n", bits);
+}
 
 /*
  * Close the SONIC device
@@ -120,6 +138,9 @@ static int sonic_close(struct net_device
 	/*
 	 * stop the SONIC, disable interrupts
 	 */
+	SONIC_WRITE(SONIC_CMD, SONIC_CR_RXDIS);
+	sonic_quiesce(dev, SONIC_CR_ALL);
+
 	SONIC_WRITE(SONIC_IMR, 0);
 	SONIC_WRITE(SONIC_ISR, 0x7fff);
 	SONIC_WRITE(SONIC_CMD, SONIC_CR_RST);
@@ -159,6 +180,9 @@ static void sonic_tx_timeout(struct net_
 	 * put the Sonic into software-reset mode and
 	 * disable all interrupts before releasing DMA buffers
 	 */
+	SONIC_WRITE(SONIC_CMD, SONIC_CR_RXDIS);
+	sonic_quiesce(dev, SONIC_CR_ALL);
+
 	SONIC_WRITE(SONIC_IMR, 0);
 	SONIC_WRITE(SONIC_ISR, 0x7fff);
 	SONIC_WRITE(SONIC_CMD, SONIC_CR_RST);
@@ -638,6 +662,7 @@ static int sonic_init(struct net_device
 	 */
 	SONIC_WRITE(SONIC_CMD, 0);
 	SONIC_WRITE(SONIC_CMD, SONIC_CR_RXDIS);
+	sonic_quiesce(dev, SONIC_CR_ALL);
 
 	/*
 	 * initialize the receive resource area
--- a/drivers/net/ethernet/natsemi/sonic.h
+++ b/drivers/net/ethernet/natsemi/sonic.h
@@ -109,6 +109,9 @@
 #define SONIC_CR_TXP            0x0002
 #define SONIC_CR_HTX            0x0001
 
+#define SONIC_CR_ALL (SONIC_CR_LCAM | SONIC_CR_RRRA | \
+		      SONIC_CR_RXEN | SONIC_CR_TXP)
+
 /*
  * SONIC data configuration bits
  */