linux/Documentation/gpu/drm-kms-helpers.rst
Sean Paul 1452c25b0e drm: Add helpers to kick off self refresh mode in drivers
This patch adds a new drm helper library to help drivers implement
self refresh. Drivers choosing to use it will register crtcs and
will receive callbacks when it's time to enter or exit self refresh
mode.

In its current form, it has a timer which will trigger after a
driver-specified amount of inactivity. When the timer triggers, the
helpers will submit a new atomic commit to shut the refreshing pipe
off. On the next atomic commit, the drm core will revert the self
refresh state and bring everything back up to be actively driven.

From the driver's perspective, this works like a regular disable/enable
cycle. The driver need only check the 'self_refresh_active' state in
crtc_state. It should initiate self refresh mode on the panel and enter
an off or low-power state.

Changes in v2:
- s/psr/self_refresh/ (Daniel)
- integrated the psr exit into the commit that wakes it up (Jose/Daniel)
- made the psr state per-crtc (Jose/Daniel)
Changes in v3:
- Remove the self_refresh_(active|changed) from connector state (Daniel)
- Simplify loop in drm_self_refresh_helper_alter_state (Daniel)
- Improve self_refresh_aware comment (Daniel)
- s/self_refresh_state/self_refresh_data/ (Daniel)
Changes in v4:
- Move docbook location below panel (Daniel)
- Improve docbook with references and more detailed explanation (Daniel)
- Instead of register/unregister, use init/cleanup (Daniel)
Changes in v5:
- Resolved conflict in drm_atomic_helper.c #include block
- Resolved conflict in rst with HDCP helper docs
Changes in v6:
- Fix include ordering, clean up forward declarations (Sam)

Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190228210939.83386-2-sean@poorly.run
Link to v2: https://patchwork.freedesktop.org/patch/msgid/20190326204509.96515-1-sean@poorly.run
Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-6-sean@poorly.run
Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-6-sean@poorly.run
Link to v5: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-6-sean@poorly.run

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jose Souza <jose.souza@intel.com>
Cc: Zain Wang <wzz@rock-chips.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190612145026.191846-1-sean@poorly.run
2019-06-13 14:31:10 -04:00

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=============================
Mode Setting Helper Functions
=============================
The DRM subsystem aims for a strong separation between core code and helper
libraries. Core code takes care of general setup and teardown and decoding
userspace requests to kernel internal objects. Everything else is handled by a
large set of helper libraries, which can be combined freely to pick and choose
for each driver what fits, and avoid shared code where special behaviour is
needed.
This distinction between core code and helpers is especially strong in the
modesetting code, where there's a shared userspace ABI for all drivers. This is
in contrast to the render side, where pretty much everything (with very few
exceptions) can be considered optional helper code.
There are a few areas these helpers can grouped into:
* Helpers to implement modesetting. The important ones here are the atomic
helpers. Old drivers still often use the legacy CRTC helpers. They both share
the same set of common helper vtables. For really simple drivers (anything
that would have been a great fit in the deprecated fbdev subsystem) there's
also the simple display pipe helpers.
* There's a big pile of helpers for handling outputs. First the generic bridge
helpers for handling encoder and transcoder IP blocks. Second the panel helpers
for handling panel-related information and logic. Plus then a big set of
helpers for the various sink standards (DisplayPort, HDMI, MIPI DSI). Finally
there's also generic helpers for handling output probing, and for dealing with
EDIDs.
* The last group of helpers concerns itself with the frontend side of a display
pipeline: Planes, handling rectangles for visibility checking and scissoring,
flip queues and assorted bits.
Modeset Helper Reference for Common Vtables
===========================================
.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h
:doc: overview
.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h
:internal:
.. _drm_atomic_helper:
Atomic Modeset Helper Functions Reference
=========================================
Overview
--------
.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c
:doc: overview
Implementing Asynchronous Atomic Commit
---------------------------------------
.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c
:doc: implementing nonblocking commit
Helper Functions Reference
--------------------------
.. kernel-doc:: include/drm/drm_atomic_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c
:export:
Atomic State Reset and Initialization
-------------------------------------
.. kernel-doc:: drivers/gpu/drm/drm_atomic_state_helper.c
:doc: atomic state reset and initialization
Atomic State Helper Reference
-----------------------------
.. kernel-doc:: include/drm/drm_atomic_state_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_atomic_state_helper.c
:export:
Simple KMS Helper Reference
===========================
.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c
:doc: overview
.. kernel-doc:: include/drm/drm_simple_kms_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c
:export:
fbdev Helper Functions Reference
================================
.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c
:doc: fbdev helpers
.. kernel-doc:: include/drm/drm_fb_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c
:export:
format Helper Functions Reference
=================================
.. kernel-doc:: drivers/gpu/drm/drm_format_helper.c
:export:
Framebuffer CMA Helper Functions Reference
==========================================
.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c
:doc: framebuffer cma helper functions
.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c
:export:
Framebuffer GEM Helper Reference
================================
.. kernel-doc:: drivers/gpu/drm/drm_gem_framebuffer_helper.c
:doc: overview
.. kernel-doc:: drivers/gpu/drm/drm_gem_framebuffer_helper.c
:export:
.. _drm_bridges:
Bridges
=======
Overview
--------
.. kernel-doc:: drivers/gpu/drm/drm_bridge.c
:doc: overview
Default bridge callback sequence
--------------------------------
.. kernel-doc:: drivers/gpu/drm/drm_bridge.c
:doc: bridge callbacks
Bridge Helper Reference
-------------------------
.. kernel-doc:: include/drm/drm_bridge.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_bridge.c
:export:
Panel-Bridge Helper Reference
-----------------------------
.. kernel-doc:: drivers/gpu/drm/bridge/panel.c
:export:
.. _drm_panel_helper:
Panel Helper Reference
======================
.. kernel-doc:: drivers/gpu/drm/drm_panel.c
:doc: drm panel
.. kernel-doc:: include/drm/drm_panel.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_panel.c
:export:
.. kernel-doc:: drivers/gpu/drm/drm_panel_orientation_quirks.c
:export:
Panel Self Refresh Helper Reference
===================================
.. kernel-doc:: drivers/gpu/drm/drm_self_refresh_helper.c
:doc: overview
.. kernel-doc:: drivers/gpu/drm/drm_self_refresh_helper.c
:export:
HDCP Helper Functions Reference
===============================
.. kernel-doc:: drivers/gpu/drm/drm_hdcp.c
:export:
Display Port Helper Functions Reference
=======================================
.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c
:doc: dp helpers
.. kernel-doc:: include/drm/drm_dp_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c
:export:
Display Port CEC Helper Functions Reference
===========================================
.. kernel-doc:: drivers/gpu/drm/drm_dp_cec.c
:doc: dp cec helpers
.. kernel-doc:: drivers/gpu/drm/drm_dp_cec.c
:export:
Display Port Dual Mode Adaptor Helper Functions Reference
=========================================================
.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c
:doc: dp dual mode helpers
.. kernel-doc:: include/drm/drm_dp_dual_mode_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c
:export:
Display Port MST Helpers
========================
Overview
--------
.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c
:doc: dp mst helper
.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c
:doc: Branch device and port refcounting
Functions Reference
-------------------
.. kernel-doc:: include/drm/drm_dp_mst_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c
:export:
Topology Lifetime Internals
---------------------------
These functions aren't exported to drivers, but are documented here to help make
the MST topology helpers easier to understand
.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c
:functions: drm_dp_mst_topology_try_get_mstb drm_dp_mst_topology_get_mstb
drm_dp_mst_topology_put_mstb
drm_dp_mst_topology_try_get_port drm_dp_mst_topology_get_port
drm_dp_mst_topology_put_port
drm_dp_mst_get_mstb_malloc drm_dp_mst_put_mstb_malloc
MIPI DSI Helper Functions Reference
===================================
.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c
:doc: dsi helpers
.. kernel-doc:: include/drm/drm_mipi_dsi.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c
:export:
Display Stream Compression Helper Functions Reference
=====================================================
.. kernel-doc:: drivers/gpu/drm/drm_dsc.c
:doc: dsc helpers
.. kernel-doc:: include/drm/drm_dsc.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_dsc.c
:export:
Output Probing Helper Functions Reference
=========================================
.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c
:doc: output probing helper overview
.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c
:export:
EDID Helper Functions Reference
===============================
.. kernel-doc:: include/drm/drm_edid.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_edid.c
:export:
SCDC Helper Functions Reference
===============================
.. kernel-doc:: drivers/gpu/drm/drm_scdc_helper.c
:doc: scdc helpers
.. kernel-doc:: include/drm/drm_scdc_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_scdc_helper.c
:export:
HDMI Infoframes Helper Reference
================================
Strictly speaking this is not a DRM helper library but generally useable
by any driver interfacing with HDMI outputs like v4l or alsa drivers.
But it nicely fits into the overall topic of mode setting helper
libraries and hence is also included here.
.. kernel-doc:: include/linux/hdmi.h
:internal:
.. kernel-doc:: drivers/video/hdmi.c
:export:
Rectangle Utilities Reference
=============================
.. kernel-doc:: include/drm/drm_rect.h
:doc: rect utils
.. kernel-doc:: include/drm/drm_rect.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_rect.c
:export:
Flip-work Helper Reference
==========================
.. kernel-doc:: include/drm/drm_flip_work.h
:doc: flip utils
.. kernel-doc:: include/drm/drm_flip_work.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_flip_work.c
:export:
Auxiliary Modeset Helpers
=========================
.. kernel-doc:: drivers/gpu/drm/drm_modeset_helper.c
:doc: aux kms helpers
.. kernel-doc:: drivers/gpu/drm/drm_modeset_helper.c
:export:
OF/DT Helpers
=============
.. kernel-doc:: drivers/gpu/drm/drm_of.c
:doc: overview
.. kernel-doc:: drivers/gpu/drm/drm_of.c
:export:
Legacy Plane Helper Reference
=============================
.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c
:doc: overview
.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c
:export:
Legacy CRTC/Modeset Helper Functions Reference
==============================================
.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c
:doc: overview
.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c
:export:
SHMEM GEM Helper Reference
==========================
.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
:doc: overview
.. kernel-doc:: include/drm/drm_gem_shmem_helper.h
:internal:
.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
:export: