From a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 5 Aug 2026 07:52:36 -0700 Subject: workqueue: skip the node_nr_active update for non-unbound workqueues apply_wqattrs_commit() updates node_nr_active->max unconditionally. wq->node_nr_active[] is only allocated for unbound workqueues, so guard the call before per-cpu workqueues start using this path. No functional change: only unbound workqueues reach apply_wqattrs_*() today. Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- Documentation/userspace-api/media/intro.rst | 46 +++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/userspace-api/media/intro.rst (limited to 'Documentation/userspace-api/media/intro.rst') diff --git a/Documentation/userspace-api/media/intro.rst b/Documentation/userspace-api/media/intro.rst new file mode 100644 index 000000000..4a6bd665b --- /dev/null +++ b/Documentation/userspace-api/media/intro.rst @@ -0,0 +1,46 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +Introduction +============ + +This document covers the Linux Kernel to Userspace API's used by video +and radio streaming devices, including video cameras, analog and digital +TV receiver cards, AM/FM receiver cards, Software Defined Radio (SDR), +streaming capture and output devices, codec devices and remote controllers. + +A typical media device hardware is shown at :ref:`typical_media_device`. + +.. _typical_media_device: + +.. kernel-figure:: typical_media_device.svg + :alt: typical_media_device.svg + :align: center + + Typical Media Device + +The media infrastructure API was designed to control such devices. It is +divided into five parts. + +1. The :ref:`first part ` covers radio, video capture and output, + cameras, analog TV devices and codecs. + +2. The :ref:`second part ` covers the API used for digital TV and + Internet reception via one of the several digital tv standards. While it is + called as DVB API, in fact it covers several different video standards + including DVB-T/T2, DVB-S/S2, DVB-C, ATSC, ISDB-T, ISDB-S, DTMB, etc. The + complete list of supported standards can be found at + :c:type:`fe_delivery_system`. + +3. The :ref:`third part ` covers the Remote Controller API. + +4. The :ref:`fourth part ` covers the Media Controller API. + +5. The :ref:`fifth part ` covers the CEC (Consumer Electronics Control) API. + +It should also be noted that a media device may also have audio components, like +mixers, PCM capture, PCM playback, etc, which are controlled via ALSA API. For +additional information and for the latest development code, see: +`https://linuxtv.org `__. For discussing improvements, +reporting troubles, sending new drivers, etc, please mail to: `Linux Media +Mailing List (LMML) `__. -- cgit v1.3.1