iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/Documentation/admin-guide/device-mapper/dm-flakey.rst b/Documentation/admin-guide/device-mapper/dm-flakey.rst
new file mode 100644
index 000000000..f967c5fea
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-flakey.rst
@@ -0,0 +1,88 @@
+=========
+dm-flakey
+=========
+
+This target is the same as the linear target except that it exhibits
+unreliable behaviour periodically.  It's been found useful in simulating
+failing devices for testing purposes.
+
+Starting from the time the table is loaded, the device is available for
+<up interval> seconds, then exhibits unreliable behaviour for <down
+interval> seconds, and then this cycle repeats.
+
+Also, consider using this in combination with the dm-delay target too,
+which can delay reads and writes and/or send them to different
+underlying devices.
+
+Table parameters
+----------------
+
+::
+
+  <dev path> <offset> <up interval> <down interval> \
+    [<num_features> [<feature arguments>]]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device, or a
+        "major:minor" device-number.
+    <offset>:
+        Starting sector within the device.
+    <up interval>:
+        Number of seconds device is available.
+    <down interval>:
+        Number of seconds device returns errors.
+
+Optional feature parameters:
+
+  If no feature parameters are present, during the periods of
+  unreliability, all I/O returns errors.
+
+  error_reads:
+	All read I/O is failed with an error signalled.
+	Write I/O is handled correctly.
+
+  drop_writes:
+	All write I/O is silently ignored.
+	Read I/O is handled correctly.
+
+  error_writes:
+	All write I/O is failed with an error signalled.
+	Read I/O is handled correctly.
+
+  corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
+	During <down interval>, replace <Nth_byte> of the data of
+	each matching bio with <value>.
+
+    <Nth_byte>:
+	The offset of the byte to replace.
+	Counting starts at 1, to replace the first byte.
+    <direction>:
+	Either 'r' to corrupt reads or 'w' to corrupt writes.
+	'w' is incompatible with drop_writes.
+    <value>:
+	The value (from 0-255) to write.
+    <flags>:
+	Perform the replacement only if bio->bi_opf has all the
+	selected flags set.
+
+  random_read_corrupt <probability>
+	During <down interval>, replace random byte in a read bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+  random_write_corrupt <probability>
+	During <down interval>, replace random byte in a write bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+Examples:
+
+Replaces the 32nd byte of READ bios with the value 1::
+
+  corrupt_bio_byte 32 r 1 0
+
+Replaces the 224th byte of REQ_META (=32) bios with the value 0::
+
+  corrupt_bio_byte 224 w 0 32