netdev - [PATCH net-next 03/27] net: mvpp2: handle too large value in mvpp2_rx_time_coal

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Message-Id: <1482318994-23488-4-git-send-email-thomas.petazzoni@free-electrons.com>
Date:   Wed, 21 Dec 2016 12:16:10 +0100
From:   Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
To:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     Nadav Haklai <nadavh@...vell.com>, Hanna Hawa <hannah@...vell.com>,
        Yehuda Yitschak <yehuday@...vell.com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Gregory Clement <gregory.clement@...e-electrons.com>,
        linux-arm-kernel@...ts.infradead.org,
        Stefan Chulski <stefanc@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Subject: [PATCH net-next 03/27] net: mvpp2: handle too large value in mvpp2_rx_time_coal_set()

When configuring the MVPP2_ISR_RX_THRESHOLD_REG with the RX coalescing
time threshold, we do not check for the maximum allowed value supported
by the driver, which means we might overflow and use a bogus value. This
commit adds a check for this situation, and if a value higher than what
is supported by the hardware is provided, then we use the maximum value
supported by the hardware.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
---
 drivers/net/ethernet/marvell/mvpp2.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/marvell/mvpp2.c b/drivers/net/ethernet/marvell/mvpp2.c
index 4c9e3ea..12edefe 100644
--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -154,6 +154,7 @@
 
 /* Interrupt Cause and Mask registers */
 #define MVPP2_ISR_RX_THRESHOLD_REG(rxq)		(0x5200 + 4 * (rxq))
+#define     MVPP2_MAX_ISR_RX_THRESHOLD		0xfffff0
 #define MVPP2_ISR_RXQ_GROUP_REG(rxq)		(0x5400 + 4 * (rxq))
 #define MVPP2_ISR_ENABLE_REG(port)		(0x5420 + 4 * (port))
 #define     MVPP2_ISR_ENABLE_INTERRUPT(mask)	((mask) & 0xffff)
@@ -4397,6 +4398,12 @@ static void mvpp2_rx_time_coal_set(struct mvpp2_port *port,
 	u32 val;
 
 	val = (port->priv->tclk / USEC_PER_SEC) * usec;
+
+	if (val > MVPP2_MAX_ISR_RX_THRESHOLD) {
+		val = MVPP2_MAX_ISR_RX_THRESHOLD;
+		usec = (val * USEC_PER_SEC) / port->priv->tclk;
+	}
+
 	mvpp2_write(port->priv, MVPP2_ISR_RX_THRESHOLD_REG(rxq->id), val);
 
 	rxq->time_coal = usec;
-- 
2.7.4