[PATCH 3/3] drm/doc: document recommended component helper usage

[Daniel Vetter]

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

Cc: Russell King - ARM Linux admin <linux at armlinux.org.uk>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 Documentation/driver-api/component.rst |  2 ++
 Documentation/gpu/drm-internals.rst    |  5 +++++
 drivers/gpu/drm/drm_drv.c              | 14 ++++++++++++++
 3 files changed, 21 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 381581b01d48..aae413003705 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -456,6 +456,20 @@ 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>`. 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(). For consistency and easier sharing of
+ * components across drivers 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.
+ */
+
 /**
  * drm_dev_init - Initialise new DRM device
  * @dev: DRM device
-- 
2.20.1