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, 94 insertions, 0 deletions

diff --git a/Documentation/gpu/amdgpu/ptl.rst b/Documentation/gpu/amdgpu/ptl.rst
new file mode 100644
index 000000000..c7f16dea7
--- /dev/null
+++ b/Documentation/gpu/amdgpu/ptl.rst
@@ -0,0 +1,94 @@
+=======================================
+Peak Tops Limiter (PTL) sysfs Interface
+=======================================
+
+Overview
+--------
+The Peak Tops Limiter (PTL) sysfs interface enables users to control and
+configure the PTL feature for each GPU individually.  All PTL-related
+sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where
+`X` is the GPU index.  Through these files, users can enable or disable
+PTL, set preferred data formats, and query supported formats for each GPU.
+
+PTL sysfs files
+----------------
+The following files are available under `/sys/class/drm/cardX/device/ptl/`:
+
+- `ptl_enable`
+- `ptl_format`
+- `ptl_supported_formats`
+
+PTL Enable/Disable
+------------------
+File: `ptl_enable`
+Type: Read/Write (rw)
+
+Read: Returns the current PTL status as a string: `enabled` if PTL
+is active, or `disabled` if inactive.
+
+Write:
+
+- Write `1` or `enabled` to enable PTL
+- Write `0` or `disabled` to disable PTL
+
+Examples::
+
+    # Query PTL status
+    cat /sys/class/drm/card1/device/ptl/ptl_enable
+    # Output: enabled
+
+    # Enable PTL
+    sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable"
+
+    # Disable PTL
+    sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable"
+
+PTL Format (Preferred Data Formats)
+-----------------------------------
+File: `ptl_format`
+Type: Read/Write (rw)
+
+Read: Returns the two preferred formats, e.g. `I8,F32`.
+
+Write: Accepts two formats separated by a comma, e.g. `I8,F32`.
+
+- Both formats must be supported and different.
+- If an invalid format is provided (not supported, or both formats are the
+  same), the driver will return "write error: Invalid argument".
+
+Examples::
+
+    # Query PTL formats
+    cat /sys/class/drm/card1/device/ptl/ptl_format
+    # Output: I8,F32
+
+    # Set PTL formats
+    sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format"
+
+Supported Formats
+-----------------
+File: `ptl_supported_formats`
+Type: Read-only (r)
+
+Read: Returns a comma-separated list of supported formats, e.g.
+`I8,F16,BF16,F32,F64`.
+
+Example::
+
+    # Check supported formats
+    cat /sys/class/drm/card1/device/ptl/ptl_supported_formats
+    # Output: I8,F16,BF16,F32,F64
+
+Behavioral Notes
+----------------
+- PTL formats can only be set when PTL is enabled.
+- If PTL is disabled, `ptl_format` returns `N/A`.
+- Only two formats can be set at a time, and they must be from the supported set and different..
+- All commands support per-GPU targeting.
+- Root permission is required to enable/disable PTL or change formats.
+- If the hardware does not support PTL, the PTL sysfs directory will not
+  be created.
+
+Implementation
+--------------
+The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`.