drm/doc: document recommended component helper usage

Now that component has docs it's worth spending a few words and
hyperlinks on recommended best practices in drm.

v2: Add another item that component shouldn't be preferred over
drm_bridge/panel and similar subsystems already providing specialized
support for specific components (Laurent). Also convert to bullet
list.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Reviewed-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190212164615.13370-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2019-02-12 17:46:15 +01:00
parent 58db702266
commit 86ab67dfcf
3 changed files with 32 additions and 0 deletions

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@ -1,3 +1,5 @@
.. _component:
======================================
Component Helper for Aggregate Drivers
======================================

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@ -93,6 +93,11 @@ Device Instance and Driver Handling
Driver Load
-----------
Component Helper Usage
~~~~~~~~~~~~~~~~~~~~~~
.. kernel-doc:: drivers/gpu/drm/drm_drv.c
:doc: component helper usage recommendations
IRQ Helper Library
~~~~~~~~~~~~~~~~~~

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@ -456,6 +456,31 @@ static void drm_fs_inode_free(struct inode *inode)
}
}
/**
* DOC: component helper usage recommendations
*
* DRM drivers that drive hardware where a logical device consists of a pile of
* independent hardware blocks are recommended to use the :ref:`component helper
* library<component>`. For consistency and better options for code reuse the
* following guidelines apply:
*
* - The entire device initialization procedure should be run from the
* &component_master_ops.master_bind callback, starting with drm_dev_init(),
* then binding all components with component_bind_all() and finishing with
* drm_dev_register().
*
* - The opaque pointer passed to all components through component_bind_all()
* should point at &struct drm_device of the device instance, not some driver
* specific private structure.
*
* - The component helper fills the niche where further standardization of
* interfaces is not practical. When there already is, or will be, a
* standardized interface like &drm_bridge or &drm_panel, providing its own
* functions to find such components at driver load time, like
* drm_of_find_panel_or_bridge(), then the component helper should not be
* used.
*/
/**
* drm_dev_init - Initialise new DRM device
* @dev: DRM device