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| author | Kees Cook <kees+treewide@kernel.org> | 2026-09-02 15:31:14 -0700 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2026-09-04 21:37:00 -0700 |
| commit | 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch) | |
| tree | c65086f9bdcd48c6360fb7cb4598bca084da1f32 /Documentation/admin-guide/media/remote-controller.rst | |
| download | linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip | |
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci
This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.
Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.
Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'Documentation/admin-guide/media/remote-controller.rst')
| -rw-r--r-- | Documentation/admin-guide/media/remote-controller.rst | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/Documentation/admin-guide/media/remote-controller.rst b/Documentation/admin-guide/media/remote-controller.rst new file mode 100644 index 000000000..188944b00 --- /dev/null +++ b/Documentation/admin-guide/media/remote-controller.rst @@ -0,0 +1,76 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================================== +Infrared remote control support in video4linux drivers +====================================================== + +Authors: Gerd Hoffmann, Mauro Carvalho Chehab + +Basics +====== + +Most analog and digital TV boards support remote controllers. Several of +them have a microprocessor that receives the IR carriers, convert into +pulse/space sequences and then to scan codes, returning such codes to +userspace ("scancode mode"). Other boards return just the pulse/space +sequences ("raw mode"). + +The support for remote controller in scancode mode is provided by the +standard Linux input layer. The support for raw mode is provided via LIRC. + +In order to check the support and test it, it is suggested to download +the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_. It provides +two tools to handle remote controllers: + +- ir-keytable: provides a way to query the remote controller, list the + protocols it supports, enable in-kernel support for IR decoder or + switch the protocol and to test the reception of scan codes; + +- ir-ctl: provide tools to handle remote controllers that support raw mode + via LIRC interface. + +Usually, the remote controller module is auto-loaded when the TV card is +detected. However, for a few devices, you need to manually load the +ir-kbd-i2c module. + +How it works +============ + +The modules register the remote as keyboard within the linux input +layer, i.e. you'll see the keys of the remote as normal key strokes +(if CONFIG_INPUT_KEYBOARD is enabled). + +Using the event devices (CONFIG_INPUT_EVDEV) it is possible for +applications to access the remote via /dev/input/event<n> devices. +The udev/systemd will automatically create the devices. If you install +the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_, it may also +automatically load a different keytable than the default one. Please see +`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ ir-keytable.1 +man page for details. + +The ir-keytable tool is nice for trouble shooting, i.e. to check +whenever the input device is really present, which of the devices it +is, check whenever pressing keys on the remote actually generates +events and the like. You can also use any other input utility that changes +the keymaps, like the input kbd utility. + + +Using with lircd +---------------- + +The latest versions of the lircd daemon supports reading events from the +linux input layer (via event device). It also supports receiving IR codes +in lirc mode. + + +Using without lircd +------------------- + +Xorg recognizes several IR keycodes that have its numerical value lower +than 247. With the advent of Wayland, the input driver got updated too, +and should now accept all keycodes. Yet, you may want to just reassign +the keycodes to something that your favorite media application likes. + +This can be done by setting +`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ to load your own +keytable in runtime. Please read ir-keytable.1 man page for details. |
