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, 86 insertions, 0 deletions

diff --git a/Documentation/fb/internals.rst b/Documentation/fb/internals.rst
new file mode 100644
index 000000000..696b50aa7
--- /dev/null
+++ b/Documentation/fb/internals.rst
@@ -0,0 +1,86 @@
+=============================
+Frame Buffer device internals
+=============================
+
+This is a first start for some documentation about frame buffer device
+internals.
+
+Authors:
+
+- Geert Uytterhoeven <geert@linux-m68k.org>, 21 July 1998
+- James Simmons <jsimmons@user.sf.net>, Nov 26 2002
+
+--------------------------------------------------------------------------------
+
+Structures used by the frame buffer device API
+==============================================
+
+The following structures play a role in the game of frame buffer devices. They
+are defined in <linux/fb.h>.
+
+1. Outside the kernel (user space)
+
+  - struct fb_fix_screeninfo
+
+    Device independent unchangeable information about a frame buffer device and
+    a specific video mode. This can be obtained using the FBIOGET_FSCREENINFO
+    ioctl.
+
+  - struct fb_var_screeninfo
+
+    Device independent changeable information about a frame buffer device and a
+    specific video mode. This can be obtained using the FBIOGET_VSCREENINFO
+    ioctl, and updated with the FBIOPUT_VSCREENINFO ioctl. If you want to pan
+    the screen only, you can use the FBIOPAN_DISPLAY ioctl.
+
+  - struct fb_cmap
+
+    Device independent colormap information. You can get and set the colormap
+    using the FBIOGETCMAP and FBIOPUTCMAP ioctls.
+
+
+2. Inside the kernel
+
+  - struct fb_info
+
+    Generic information, API and low level information about a specific frame
+    buffer device instance (slot number, board address, ...).
+
+  - struct `par`
+
+    Device dependent information that uniquely defines the video mode for this
+    particular piece of hardware.
+
+
+Visuals used by the frame buffer device API
+===========================================
+
+
+Monochrome (FB_VISUAL_MONO01 and FB_VISUAL_MONO10)
+--------------------------------------------------
+Each pixel is either black or white.
+
+
+Pseudo color (FB_VISUAL_PSEUDOCOLOR and FB_VISUAL_STATIC_PSEUDOCOLOR)
+---------------------------------------------------------------------
+The whole pixel value is fed through a programmable lookup table that has one
+color (including red, green, and blue intensities) for each possible pixel
+value, and that color is displayed.
+
+
+True color (FB_VISUAL_TRUECOLOR)
+--------------------------------
+The pixel value is broken up into red, green, and blue fields.
+
+
+Direct color (FB_VISUAL_DIRECTCOLOR)
+------------------------------------
+The pixel value is broken up into red, green, and blue fields, each of which
+are looked up in separate red, green, and blue lookup tables.
+
+
+Grayscale displays
+------------------
+Grayscale and static grayscale are special variants of pseudo color and static
+pseudo color, where the red, green and blue components are always equal to
+each other.