linux-kernel - [PATCH 3.16 17/72] can: mcp251x: mcp251x_hw_reset(): allow more time after a reset

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Message-ID: <lsq.1575813165.957212105@decadent.org.uk>
Date:   Sun, 08 Dec 2019 13:53:01 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Marc Kleine-Budde" <mkl@...gutronix.de>,
        "Sean Nyekjaer" <sean@...nix.com>
Subject: [PATCH 3.16 17/72] can: mcp251x: mcp251x_hw_reset(): allow more
 time after a reset

3.16.79-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Marc Kleine-Budde <mkl@...gutronix.de>

commit d84ea2123f8d27144e3f4d58cd88c9c6ddc799de upstream.

Some boards take longer than 5ms to power up after a reset, so allow
some retries attempts before giving up.

Fixes: ff06d611a31c ("can: mcp251x: Improve mcp251x_hw_reset()")
Tested-by: Sean Nyekjaer <sean@...nix.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/net/can/spi/mcp251x.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

--- a/drivers/net/can/spi/mcp251x.c
+++ b/drivers/net/can/spi/mcp251x.c
@@ -626,7 +626,7 @@ static int mcp251x_setup(struct net_devi
 static int mcp251x_hw_reset(struct spi_device *spi)
 {
 	struct mcp251x_priv *priv = spi_get_drvdata(spi);
-	u8 reg;
+	unsigned long timeout;
 	int ret;
 
 	/* Wait for oscillator startup timer after power up */
@@ -640,10 +640,19 @@ static int mcp251x_hw_reset(struct spi_d
 	/* Wait for oscillator startup timer after reset */
 	mdelay(MCP251X_OST_DELAY_MS);
 	
-	reg = mcp251x_read_reg(spi, CANSTAT);
-	if ((reg & CANCTRL_REQOP_MASK) != CANCTRL_REQOP_CONF)
-		return -ENODEV;
+	/* Wait for reset to finish */
+	timeout = jiffies + HZ;
+	while ((mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK) !=
+	       CANCTRL_REQOP_CONF) {
+		usleep_range(MCP251X_OST_DELAY_MS * 1000,
+			     MCP251X_OST_DELAY_MS * 1000 * 2);
 
+		if (time_after(jiffies, timeout)) {
+			dev_err(&spi->dev,
+				"MCP251x didn't enter in conf mode after reset\n");
+			return -EBUSY;
+		}
+	}
 	return 0;
 }