This is a note to let you know that I've just added the patch titled
iio: adc: mcp3422: fix locking scope
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 3f1093d83d7164e4705e4232ccf76da54adfda85 Mon Sep 17 00:00:00 2001
From: Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx>
Date: Wed, 19 Aug 2020 09:55:25 +0200
Subject: iio: adc: mcp3422: fix locking scope
Locking should be held for the entire reading sequence involving setting
the channel, waiting for the channel switch and reading from the
channel.
If not, reading from a channel can result mixing with the reading from
another channel.
Fixes: 07914c84ba30 ("iio: adc: Add driver for Microchip MCP3422/3/4 high resolution ADC")
Signed-off-by: Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx>
Link: https://lore.kernel.org/r/20200819075525.1395248-1-angelo.compagnucci@xxxxxxxxx
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
drivers/iio/adc/mcp3422.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
index 5f1706d1c3c0..219adac2384b 100644
--- a/drivers/iio/adc/mcp3422.c
+++ b/drivers/iio/adc/mcp3422.c
@@ -96,16 +96,12 @@ static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
{
int ret;
- mutex_lock(&adc->lock);
-
ret = i2c_master_send(adc->i2c, &newconfig, 1);
if (ret > 0) {
adc->config = newconfig;
ret = 0;
}
- mutex_unlock(&adc->lock);
-
return ret;
}
@@ -138,6 +134,8 @@ static int mcp3422_read_channel(struct mcp3422 *adc,
u8 config;
u8 req_channel = channel->channel;
+ mutex_lock(&adc->lock);
+
if (req_channel != MCP3422_CHANNEL(adc->config)) {
config = adc->config;
config &= ~MCP3422_CHANNEL_MASK;
@@ -150,7 +148,11 @@ static int mcp3422_read_channel(struct mcp3422 *adc,
msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
}
- return mcp3422_read(adc, value, &config);
+ ret = mcp3422_read(adc, value, &config);
+
+ mutex_unlock(&adc->lock);
+
+ return ret;
}
static int mcp3422_read_raw(struct iio_dev *iio,
--
2.28.0
