From 3d62c78a6eb9a7d67bace9622b66ad51e81c5f9b Mon Sep 17 00:00:00 2001
From: Matt Fornero <matt.fornero@mathworks.com>
Date: Tue, 5 Sep 2017 16:34:10 +0200
Subject: [PATCH] iio: core: Return error for failed read_reg
Git-commit: 3d62c78a6eb9a7d67bace9622b66ad51e81c5f9b
Patch-mainline: v4.14-rc4
References: bsc#1051510

If an IIO device returns an error code for a read access via debugfs, it
is currently ignored by the IIO core (other than emitting an error
message). Instead, return this error code to user space, so upper layers
can detect it correctly.

Signed-off-by: Matt Fornero <matt.fornero@mathworks.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/iio/industrialio-core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -310,8 +310,10 @@ static ssize_t iio_debugfs_read_reg(stru
 	ret = indio_dev->info->debugfs_reg_access(indio_dev,
 						  indio_dev->cached_reg_addr,
 						  0, &val);
-	if (ret)
+	if (ret) {
 		dev_err(indio_dev->dev.parent, "%s: read failed\n", __func__);
+		return ret;
+	}
 
 	len = snprintf(buf, sizeof(buf), "0x%X\n", val);