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| author | Donggeun Yoo <donggeunyoo.kernel@gmail.com> | 2026-09-02 00:21:26 +0900 |
|---|---|---|
| committer | Jonathan Cameron <jonathan.cameron@oss.qualcomm.com> | 2026-09-07 02:24:53 +0100 |
| commit | e24328974a88aa8541e94e8bb8dfa2ade1b3c45d (patch) | |
| tree | 43a2533acc955d11f5cb8be1ecba0ab8ba4cbb1e /Documentation/userspace-api/ioctl/ioctl-decoding.rst | |
| download | linux-stable-e24328974a88aa8541e94e8bb8dfa2ade1b3c45d.tar.gz linux-stable-e24328974a88aa8541e94e8bb8dfa2ade1b3c45d.zip | |
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>
Diffstat (limited to 'Documentation/userspace-api/ioctl/ioctl-decoding.rst')
| -rw-r--r-- | Documentation/userspace-api/ioctl/ioctl-decoding.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/userspace-api/ioctl/ioctl-decoding.rst b/Documentation/userspace-api/ioctl/ioctl-decoding.rst new file mode 100644 index 000000000..380d6bb3e --- /dev/null +++ b/Documentation/userspace-api/ioctl/ioctl-decoding.rst @@ -0,0 +1,31 @@ +============================== +Decoding an IOCTL Magic Number +============================== + +To decode a hex IOCTL code: + +Most architectures use this generic format, but check +include/ARCH/ioctl.h for specifics, e.g. powerpc +uses 3 bits to encode read/write and 13 bits for size. + + ====== ================================== + bits meaning + ====== ================================== + 31-30 00 - no parameters: uses _IO macro + 10 - read: _IOR + 01 - write: _IOW + 11 - read/write: _IOWR + + 29-16 size of arguments + + 15-8 ascii character supposedly + unique to each driver + + 7-0 function # + ====== ================================== + + +So for example 0x82187201 is a read with arg length of 0x218, +character 'r' function 1. Grepping the source reveals this is:: + + #define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2]) |