mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
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1ee1bb64f7
Fix two kernel doc warnings introduced by the recent DP audio patch:
- Add a doc line for the new "audio" field
- Remove a reference to zynqmp_dpsub.c from zynqmp.rst, as the .c file
no longer has structured comments
Fixes: 3ec5c1579305 ("drm: xlnx: zynqmp_dpsub: Add DP audio support")
Closes: https://lore.kernel.org/all/20241220154208.720d990b@canb.auug.org.au/
Reviewed-by: Vishal Sagar <vishal.sagar@amd.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241220-xilinx-dp-audio-doc-fix-v1-1-cc488996e463@ideasonboard.com
(cherry picked from commit 96b5d2e807f667320c66f41ddc1c473023a73ab2)
Signed-off-by: Maxime Ripard <mripard@kernel.org>
148 lines
4.7 KiB
ReStructuredText
148 lines
4.7 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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===============================================
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Xilinx ZynqMP Ultrascale+ DisplayPort Subsystem
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===============================================
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This subsystem handles DisplayPort video and audio output on the ZynqMP. It
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supports in-memory framebuffers with the DisplayPort DMA controller
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(xilinx-dpdma), as well as "live" video and audio from the programmable logic
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(PL). This subsystem can perform several transformations, including color space
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conversion, alpha blending, and audio mixing, although not all features are
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currently supported.
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debugfs
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-------
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To support debugging and compliance testing, several test modes can be enabled
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though debugfs. The following files in /sys/kernel/debug/dri/X/DP-1/test/
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control the DisplayPort test modes:
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active:
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Writing a 1 to this file will activate test mode, and writing a 0 will
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deactivate test mode. Writing a 1 or 0 when the test mode is already
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active/inactive will re-activate/re-deactivate test mode. When test
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mode is inactive, changes made to other files will have no (immediate)
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effect, although the settings will be saved for when test mode is
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activated. When test mode is active, changes made to other files will
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apply immediately.
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custom:
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Custom test pattern value
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downspread:
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Enable/disable clock downspreading (spread-spectrum clocking) by
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writing 1/0
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enhanced:
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Enable/disable enhanced framing
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ignore_aux_errors:
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Ignore AUX errors when set to 1. Writes to this file take effect
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immediately (regardless of whether test mode is active) and affect all
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AUX transfers.
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ignore_hpd:
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Ignore hotplug events (such as cable removals or monitor link
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retraining requests) when set to 1. Writes to this file take effect
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immediately (regardless of whether test mode is active).
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laneX_preemphasis:
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Preemphasis from 0 (lowest) to 2 (highest) for lane X
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laneX_swing:
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Voltage swing from 0 (lowest) to 3 (highest) for lane X
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lanes:
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Number of lanes to use (1, 2, or 4)
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pattern:
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Test pattern. May be one of:
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video
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Use regular video input
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symbol-error
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Symbol error measurement pattern
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prbs7
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Output of the PRBS7 (x^7 + x^6 + 1) polynomial
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80bit-custom
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A custom 80-bit pattern
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cp2520
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HBR2 compliance eye pattern
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tps1
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Link training symbol pattern TPS1 (/D10.2/)
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tps2
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Link training symbol pattern TPS2
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tps3
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Link training symbol pattern TPS3 (for HBR2)
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rate:
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Rate in hertz. One of
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* 5400000000 (HBR2)
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* 2700000000 (HBR)
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* 1620000000 (RBR)
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You can dump the displayport test settings with the following command::
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for prop in /sys/kernel/debug/dri/1/DP-1/test/*; do
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printf '%-17s ' ${prop##*/}
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if [ ${prop##*/} = custom ]; then
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hexdump -C $prop | head -1
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else
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cat $prop
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fi
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done
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The output could look something like::
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active 1
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custom 00000000 00 00 00 00 00 00 00 00 00 00 |..........|
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downspread 0
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enhanced 1
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ignore_aux_errors 1
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ignore_hpd 1
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lane0_preemphasis 0
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lane0_swing 3
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lane1_preemphasis 0
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lane1_swing 3
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lanes 2
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pattern prbs7
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rate 1620000000
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The recommended test procedure is to connect the board to a monitor,
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configure test mode, activate test mode, and then disconnect the cable
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and connect it to your test equipment of choice. For example, one
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sequence of commands could be::
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echo 1 > /sys/kernel/debug/dri/1/DP-1/test/enhanced
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echo tps1 > /sys/kernel/debug/dri/1/DP-1/test/pattern
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echo 1620000000 > /sys/kernel/debug/dri/1/DP-1/test/rate
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echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_aux_errors
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echo 1 > /sys/kernel/debug/dri/1/DP-1/test/ignore_hpd
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echo 1 > /sys/kernel/debug/dri/1/DP-1/test/active
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at which point the cable could be disconnected from the monitor.
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Internals
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---------
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.h
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dpsub.h
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.h
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_disp.c
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_dp.c
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.. kernel-doc:: drivers/gpu/drm/xlnx/zynqmp_kms.c
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