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, 173 insertions, 0 deletions

diff --git a/Documentation/fb/pxafb.rst b/Documentation/fb/pxafb.rst
new file mode 100644
index 000000000..90177f5e7
--- /dev/null
+++ b/Documentation/fb/pxafb.rst
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+================================
+Driver for PXA25x LCD controller
+================================
+
+The driver supports the following options, either via
+options=<OPTIONS> when modular or video=pxafb:<OPTIONS> when built in.
+
+For example::
+
+	modprobe pxafb options=vmem:2M,mode:640x480-8,passive
+
+or on the kernel command line::
+
+	video=pxafb:vmem:2M,mode:640x480-8,passive
+
+vmem: VIDEO_MEM_SIZE
+
+	Amount of video memory to allocate (can be suffixed with K or M
+	for kilobytes or megabytes)
+
+mode:XRESxYRES[-BPP]
+
+	XRES == LCCR1_PPL + 1
+
+	YRES == LLCR2_LPP + 1
+
+		The resolution of the display in pixels
+
+	BPP == The bit depth. Valid values are 1, 2, 4, 8 and 16.
+
+pixclock:PIXCLOCK
+
+	Pixel clock in picoseconds
+
+left:LEFT == LCCR1_BLW + 1
+
+right:RIGHT == LCCR1_ELW + 1
+
+hsynclen:HSYNC == LCCR1_HSW + 1
+
+upper:UPPER == LCCR2_BFW
+
+lower:LOWER == LCCR2_EFR
+
+vsynclen:VSYNC == LCCR2_VSW + 1
+
+	Display margins and sync times
+
+color | mono => LCCR0_CMS
+
+	umm...
+
+active | passive => LCCR0_PAS
+
+	Active (TFT) or Passive (STN) display
+
+single | dual => LCCR0_SDS
+
+	Single or dual panel passive display
+
+4pix | 8pix => LCCR0_DPD
+
+	4 or 8 pixel monochrome single panel data
+
+hsync:HSYNC, vsync:VSYNC
+
+	Horizontal and vertical sync. 0 => active low, 1 => active
+	high.
+
+dpc:DPC
+
+	Double pixel clock. 1=>true, 0=>false
+
+outputen:POLARITY
+
+	Output Enable Polarity. 0 => active low, 1 => active high
+
+pixclockpol:POLARITY
+
+	pixel clock polarity
+	0 => falling edge, 1 => rising edge
+
+
+Overlay Support for PXA27x and later LCD controllers
+====================================================
+
+  PXA27x and later processors support overlay1 and overlay2 on-top of the
+  base framebuffer (although under-neath the base is also possible). They
+  support palette and no-palette RGB formats, as well as YUV formats (only
+  available on overlay2). These overlays have dedicated DMA channels and
+  behave in a similar way as a framebuffer.
+
+  However, there are some differences between these overlay framebuffers
+  and normal framebuffers, as listed below:
+
+  1. overlay can start at a 32-bit word aligned position within the base
+     framebuffer, which means they have a start (x, y). This information
+     is encoded into var->nonstd (no, var->xoffset and var->yoffset are
+     not for such purpose).
+
+  2. overlay framebuffer is allocated dynamically according to specified
+     'struct fb_var_screeninfo', the amount is decided by::
+
+	var->xres_virtual * var->yres_virtual * bpp
+
+     bpp = 16 -- for RGB565 or RGBT555
+
+     bpp = 24 -- for YUV444 packed
+
+     bpp = 24 -- for YUV444 planar
+
+     bpp = 16 -- for YUV422 planar (1 pixel = 1 Y + 1/2 Cb + 1/2 Cr)
+
+     bpp = 12 -- for YUV420 planar (1 pixel = 1 Y + 1/4 Cb + 1/4 Cr)
+
+     NOTE:
+
+     a. overlay does not support panning in x-direction, thus
+	var->xres_virtual will always be equal to var->xres
+
+     b. line length of overlay(s) must be on a 32-bit word boundary,
+	for YUV planar modes, it is a requirement for the component
+	with minimum bits per pixel,  e.g. for YUV420, Cr component
+	for one pixel is actually 2-bits, it means the line length
+	should be a multiple of 16-pixels
+
+     c. starting horizontal position (XPOS) should start on a 32-bit
+	word boundary, otherwise the fb_check_var() will just fail.
+
+     d. the rectangle of the overlay should be within the base plane,
+	otherwise fail
+
+     Applications should follow the sequence below to operate an overlay
+     framebuffer:
+
+	 a. open("/dev/fb[1-2]", ...)
+	 b. ioctl(fd, FBIOGET_VSCREENINFO, ...)
+	 c. modify 'var' with desired parameters:
+
+	    1) var->xres and var->yres
+	    2) larger var->yres_virtual if more memory is required,
+	       usually for double-buffering
+	    3) var->nonstd for starting (x, y) and color format
+	    4) var->{red, green, blue, transp} if RGB mode is to be used
+
+	 d. ioctl(fd, FBIOPUT_VSCREENINFO, ...)
+	 e. ioctl(fd, FBIOGET_FSCREENINFO, ...)
+	 f. mmap
+	 g. ...
+
+  3. for YUV planar formats, these are actually not supported within the
+     framebuffer framework, application has to take care of the offsets
+     and lengths of each component within the framebuffer.
+
+  4. var->nonstd is used to pass starting (x, y) position and color format,
+     the detailed bit fields are shown below::
+
+      31                23  20         10          0
+       +-----------------+---+----------+----------+
+       |  ... unused ... |FOR|   XPOS   |   YPOS   |
+       +-----------------+---+----------+----------+
+
+     FOR  - color format, as defined by OVERLAY_FORMAT_* in pxafb.h
+
+	  - 0 - RGB
+	  - 1 - YUV444 PACKED
+	  - 2 - YUV444 PLANAR
+	  - 3 - YUV422 PLANAR
+	  - 4 - YUR420 PLANAR
+
+     XPOS - starting horizontal position
+
+     YPOS - starting vertical position