linux-kernel - [PATCH 2.6.26-rc-mm] gpio max7301: check spi

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Message-Id: <200806271837.45968.david-b@pacbell.net>
Date:	Fri, 27 Jun 2008 18:37:45 -0700
From:	David Brownell <david-b@...bell.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>,
	lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH 2.6.26-rc-mm] gpio max7301: check spi_setup() return code, cleanup

From: Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>

Fix inaccuracies in comments, check spi_setup() return code, mask off high 
byte in max7301_read(). Thanks to David Brownell for the review.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
Same as what Guennadi sent 12-june, but with a minor comment tweak.

 drivers/gpio/max7301.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/gpio/max7301.c	2008-06-27 18:29:35.000000000 -0700
+++ b/drivers/gpio/max7301.c	2008-06-27 18:30:23.000000000 -0700
@@ -71,7 +71,7 @@ struct max7301 {
  *
  * A write to the MAX7301 means one message with one transfer
  *
- * Returns 0 if successfull or a negative value on error
+ * Returns 0 if successful or a negative value on error
  */
 static int max7301_write(struct spi_device *spi, unsigned int reg, unsigned int val)
 {
@@ -84,9 +84,9 @@ static int max7301_write(struct spi_devi
  * @spi: The SPI device
  * @reg: Register offset
  *
- * A read from the MAX7301 means one message with two transfers
+ * A read from the MAX7301 means two transfers; here, one message each
  *
- * Returns positive 8 bit value from device if successfull or a
+ * Returns positive 8 bit value from device if successful or a
  * negative value on error
  */
 static int max7301_read(struct spi_device *spi, unsigned int reg)
@@ -99,12 +99,13 @@ static int max7301_read(struct spi_devic
 	if (ret)
 		return ret;
 	/*
-	 * FIXME: This read should write 0x0000 (=NOOP at MAX7301 side)
+	 * This relies on the fact, that a transfer with NULL tx_buf shifts out
+	 * zero bytes (=NOOP for MAX7301)
 	 */
 	ret = spi_read(spi, (u8 *)&word, sizeof(word));
 	if (ret)
 		return ret;
-	return word;
+	return word & 0xff;
 }
 
 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
@@ -224,7 +225,9 @@ static int __devinit max7301_probe(struc
 	 */
 	spi->bits_per_word = 16;
 
-	spi->master->setup(spi);
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return ret;
 
 	ts = kzalloc(sizeof(struct max7301), GFP_KERNEL);
 	if (!ts)
--
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