linux-kernel - [PATCH] max7301: fix the race between chip addition and pins reconfiguration

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Date:	Sun, 17 Aug 2008 23:24:18 +0400
From:	Dmitry Baryshkov <dbaryshkov@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	dbrownell@...rs.sourceforge.net,
	Dmitry Baryshkov <dbaryshkov@...il.com>,
	Juergen Beisert <j.beisert@...gutronix.de>,
	Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>,
	Russell King <rmk@....linux.org.uk>
Subject: [PATCH] max7301: fix the race between chip addition and pins reconfiguration

There is a small race and code ugliness in max7301: pins are
reconfigured after the chip is registered. Swap these calls
so that the device is registered in correct state.

Also this fixes the comile-time warning about unchecked gpiochip_remove.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@...il.com>
Cc: Juergen Beisert <j.beisert@...gutronix.de>
Cc: Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
Cc: Russell King <rmk@....linux.org.uk>
---
 drivers/gpio/max7301.c |   18 ++++++++----------
 1 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/max7301.c b/drivers/gpio/max7301.c
index 39c795a..c34f408 100644
--- a/drivers/gpio/max7301.c
+++ b/drivers/gpio/max7301.c
@@ -255,10 +255,6 @@ static int __devinit max7301_probe(struct spi_device *spi)
 	ts->chip.dev = &spi->dev;
 	ts->chip.owner = THIS_MODULE;
 
-	ret = gpiochip_add(&ts->chip);
-	if (ret)
-		goto exit_destroy;
-
 	/*
 	 * tristate all pins in hardware and cache the
 	 * register values for later use.
@@ -269,17 +265,19 @@ static int __devinit max7301_probe(struct spi_device *spi)
 		max7301_write(spi, 0x08 + i, 0xAA);
 		ts->port_config[i] = 0xAA;
 		for (j = 0; j < 4; j++) {
-			int idx = ts->chip.base + (i - 1) * 4 + j;
-			ret = gpio_direction_input(idx);
+			int offset = (i - 1) * 4 + j;
+			ret = max7301_direction_input(&ts->chip, offset);
 			if (ret)
-				goto exit_remove;
-			gpio_free(idx);
+				goto exit_destroy;
 		}
 	}
+
+	ret = gpiochip_add(&ts->chip);
+	if (ret)
+		goto exit_destroy;
+
 	return ret;
 
-exit_remove:
-	gpiochip_remove(&ts->chip);
 exit_destroy:
 	dev_set_drvdata(&spi->dev, NULL);
 	mutex_destroy(&ts->lock);
-- 
1.5.6.3

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