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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,
        Angelo Dureghello <angelo@kernel-space.org>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 071/111] can: flexcan: flexcan_chip_freeze(): fix chip freeze for missing bitrate
Date:   Mon, 29 Mar 2021 09:58:19 +0200
Message-Id: <20210329075617.577997837@linuxfoundation.org>
In-Reply-To: <20210329075615.186199980@linuxfoundation.org>
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From: Angelo Dureghello <angelo@kernel-space.org>

[ Upstream commit 47c5e474bc1e1061fb037d13b5000b38967eb070 ]

For cases when flexcan is built-in, bitrate is still not set at
registering. So flexcan_chip_freeze() generates:

[    1.860000] *** ZERO DIVIDE ***   FORMAT=4
[    1.860000] Current process id is 1
[    1.860000] BAD KERNEL TRAP: 00000000
[    1.860000] PC: [<402e70c8>] flexcan_chip_freeze+0x1a/0xa8

To allow chip freeze, using an hardcoded timeout when bitrate is still
not set.

Fixes: ec15e27cc890 ("can: flexcan: enable RX FIFO after FRZ/HALT valid")
Link: https://lore.kernel.org/r/20210315231510.650593-1-angelo@kernel-space.org
Signed-off-by: Angelo Dureghello <angelo@kernel-space.org>
[mkl: use if instead of ? operator]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/can/flexcan.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index b6d00dfa8b8f..7ec15cb356c0 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -544,9 +544,15 @@ static int flexcan_chip_disable(struct flexcan_priv *priv)
 static int flexcan_chip_freeze(struct flexcan_priv *priv)
 {
 	struct flexcan_regs __iomem *regs = priv->regs;
-	unsigned int timeout = 1000 * 1000 * 10 / priv->can.bittiming.bitrate;
+	unsigned int timeout;
+	u32 bitrate = priv->can.bittiming.bitrate;
 	u32 reg;
 
+	if (bitrate)
+		timeout = 1000 * 1000 * 10 / bitrate;
+	else
+		timeout = FLEXCAN_TIMEOUT_US / 10;
+
 	reg = priv->read(&regs->mcr);
 	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT;
 	priv->write(reg, &regs->mcr);
-- 
2.30.1