linux-kernel - [PATCH] of: spi: Return error from of_spi_register

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Date:	Wed, 13 Feb 2013 14:23:24 +0100
From:	Andreas Larsson <andreas@...sler.com>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	spi-devel-general@...ts.sourceforge.net,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	software@...sler.com
Subject: [PATCH] of: spi: Return error from of_spi_register_master on bad "cs-gpios" property

This makes sure that an error is returned on an incorrectly formed
"cs-gpios" property, but reports success when the "cs-gpios" property is
well formed or missing.

When holes in the cs-gpios property phandle list is used to indicate
that some other form of chipselect is to be used it is important that
failure to read a broken "cs-gpios" property does not silently fail
leading to the spi controller to use an unintended chipselect.

Signed-off-by: Andreas Larsson <andreas@...sler.com>
---

Can only be applied to devicetree/next as it builds upon the
"of: Add helper for counting phandle refernces" patch series.

 drivers/spi/spi.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 21c4748..9b5f024 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1068,8 +1068,11 @@ static int of_spi_register_master(struct spi_master *master)
 	nb = of_gpio_named_count(np, "cs-gpios");
 	master->num_chipselect = max(nb, (int)master->num_chipselect);
 
-	if (nb < 1)
+	/* Return error only for an incorrectly formed cs-gpios property */
+	if (nb == 0 || nb == -ENOENT)
 		return 0;
+	else if (nb < 0)
+		return nb;
 
 	cs = devm_kzalloc(&master->dev,
 			  sizeof(int) * master->num_chipselect,
-- 
1.7.0.4

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