[PATCH] drm/doc: document recommended component helper usage
Daniel Vetter
daniel at ffwll.ch
Tue Feb 19 11:23:44 UTC 2019
On Tue, Feb 12, 2019 at 05:46:15PM +0100, Daniel Vetter wrote:
> 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 at ideasonboard.com>
> Cc: Russell King - ARM Linux admin <linux at armlinux.org.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Merged with Maxime's irc r-b.
-Daniel
> ---
> Documentation/driver-api/component.rst | 2 ++
> Documentation/gpu/drm-internals.rst | 5 +++++
> drivers/gpu/drm/drm_drv.c | 25 +++++++++++++++++++++++++
> 3 files changed, 32 insertions(+)
>
> diff --git a/Documentation/driver-api/component.rst b/Documentation/driver-api/component.rst
> index 2da4a8f20607..57e37590733f 100644
> --- a/Documentation/driver-api/component.rst
> +++ b/Documentation/driver-api/component.rst
> @@ -1,3 +1,5 @@
> +.. _component:
> +
> ======================================
> Component Helper for Aggregate Drivers
> ======================================
> diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst
> index 3ae23a5454ac..966bd2d9f0cc 100644
> --- a/Documentation/gpu/drm-internals.rst
> +++ b/Documentation/gpu/drm-internals.rst
> @@ -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
> ~~~~~~~~~~~~~~~~~~
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 4f70cf68112f..43825a888e67 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -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
> --
> 2.20.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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