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, 147 insertions, 0 deletions

diff --git a/Documentation/gpu/zynqmp.rst b/Documentation/gpu/zynqmp.rst
new file mode 100644
index 000000000..1a6f9193d
--- /dev/null
+++ b/Documentation/gpu/zynqmp.rst
@@ -0,0 +1,147 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+===============================================
+Xilinx ZynqMP Ultrascale+ DisplayPort Subsystem
+===============================================
+
+This subsystem handles DisplayPort video and audio output on the ZynqMP. It
+supports in-memory framebuffers with the DisplayPort DMA controller
+(xilinx-dpdma), as well as "live" video and audio from the programmable logic
+(PL). This subsystem can perform several transformations, including color space
+conversion, alpha blending, and audio mixing, although not all features are
+currently supported.
+
+debugfs
+-------
+
+To support debugging and compliance testing, several test modes can be enabled
+though debugfs. The following files in /sys/kernel/debug/dri/X/DP-1/test/
+control the DisplayPort test modes:
+
+active:
+        Writing a 1 to this file will activate test mode, and writing a 0 will
+        deactivate test mode. Writing a 1 or 0 when the test mode is already
+        active/inactive will re-activate/re-deactivate test mode. When test
+        mode is inactive, changes made to other files will have no (immediate)
+        effect, although the settings will be saved for when test mode is
+        activated. When test mode is active, changes made to other files will
+        apply immediately.
+
+custom:
+        Custom test pattern value
+
+downspread:
+        Enable/disable clock downspreading (spread-spectrum clocking) by
+        writing 1/0
+
+enhanced:
+        Enable/disable enhanced framing
+
+ignore_aux_errors:
+        Ignore AUX errors when set to 1. Writes to this file take effect
+        immediately (regardless of whether test mode is active) and affect all
+        AUX transfers.
+
+ignore_hpd:
+        Ignore hotplug events (such as cable removals or monitor link
+        retraining requests) when set to 1. Writes to this file take effect
+        immediately (regardless of whether test mode is active).
+
+laneX_preemphasis:
+        Preemphasis from 0 (lowest) to 2 (highest) for lane X
+
+laneX_swing:
+        Voltage swing from 0 (lowest) to 3 (highest) for lane X
+
+lanes:
+        Number of lanes to use (1, 2, or 4)
+
+pattern:
+        Test pattern. May be one of:
+
+                video
+                        Use regular video input
+
+                symbol-error
+                        Symbol error measurement pattern
+
+                prbs7
+                        Output of the PRBS7 (x^7 + x^6 + 1) polynomial
+
+                80bit-custom
+                        A custom 80-bit pattern
+
+                cp2520
+                        HBR2 compliance eye pattern
+
+                tps1
+                        Link training symbol pattern TPS1 (/D10.2/)
+
+                tps2
+                        Link training symbol pattern TPS2
+
+                tps3
+                        Link training symbol pattern TPS3 (for HBR2)
+
+rate:
+        Rate in hertz. One of
+
+                * 5400000000 (HBR2)
+                * 2700000000 (HBR)
+                * 1620000000 (RBR)
+
+You can dump the displayport test settings with the following command::
+
+        for prop in /sys/kernel/debug/dri/1/DP-1/test/*; do
+                printf '%-17s ' ${prop##*/}
+                if [ ${prop##*/} = custom ]; then
+                        hexdump -C $prop | head -1
+                else
+                        cat $prop
+                fi
+        done
+
+The output could look something like::
+
+        active            1
+        custom            00000000  00 00 00 00 00 00 00 00  00 00                    |..........|
+        downspread        0
+        enhanced          1
+        ignore_aux_errors 1
+        ignore_hpd        1
+        lane0_preemphasis 0
+        lane0_swing       3
+        lane1_preemphasis 0
+        lane1_swing       3
+        lanes             2
+        pattern           prbs7
+        rate              1620000000
+
+The recommended test procedure is to connect the board to a monitor,
+configure test mode, activate test mode, and then disconnect the cable
+and connect it to your test equipment of choice. For example, one
+sequence of commands could be::
+
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/enhanced
+        echo tps1 > /sys/kernel/debug/dri/1/DP-1/test/pattern
+        echo 1620000000 > /sys/kernel/debug/dri/1/DP-1/test/rate
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_aux_errors
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_hpd
+        echo 1 > /sys/kernel/debug/dri/1/DP-1/test/active
+
+at which point the cable could be disconnected from the monitor.
+
+Internals
+---------
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dpsub.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.h
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.c
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dp.c
+
+.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.c