drm: Merge helper docbook into kerneldoc comments

Duplication is bad, luckily both help texts highlighted different
issues so the kerneldoc gained quite a bit!

While at it also sprinkle more references to the vtable structs around
and make it clear that legacy CRTC helpers are deprecated and which
functions to use instead.

v2: Spelling fixes and polish (Thierry).

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449218769-16577-6-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Thierry Reding <treding@nvidia.com>

Documentation/DocBook/gpu.tmpl

@@ -1830,83 +1830,7 @@ void intel_crt_init(struct drm_device *dev)
       entities.
     </para>
     <sect2>
-      <title>Helper Functions</title>
-      <itemizedlist>
-        <listitem>
-          <synopsis>int drm_crtc_helper_set_config(struct drm_mode_set *set);</synopsis>
-          <para>
-            The <function>drm_crtc_helper_set_config</function> helper function
-            is a CRTC <methodname>set_config</methodname> implementation. It
-            first tries to locate the best encoder for each connector by calling
-            the connector <methodname>best_encoder</methodname> helper
-            operation.
-          </para>
-          <para>
-            After locating the appropriate encoders, the helper function will
-            call the <methodname>mode_fixup</methodname> encoder and CRTC helper
-            operations to adjust the requested mode, or reject it completely in
-            which case an error will be returned to the application. If the new
-            configuration after mode adjustment is identical to the current
-            configuration the helper function will return without performing any
-            other operation.
-          </para>
-          <para>
-            If the adjusted mode is identical to the current mode but changes to
-            the frame buffer need to be applied, the
-            <function>drm_crtc_helper_set_config</function> function will call
-            the CRTC <methodname>mode_set_base</methodname> helper operation. If
-            the adjusted mode differs from the current mode, or if the
-            <methodname>mode_set_base</methodname> helper operation is not
-            provided, the helper function performs a full mode set sequence by
-            calling the <methodname>prepare</methodname>,
-            <methodname>mode_set</methodname> and
-            <methodname>commit</methodname> CRTC and encoder helper operations,
-            in that order.
-          </para>
-        </listitem>
-        <listitem>
-          <synopsis>void drm_helper_connector_dpms(struct drm_connector *connector, int mode);</synopsis>
-          <para>
-            The <function>drm_helper_connector_dpms</function> helper function
-            is a connector <methodname>dpms</methodname> implementation that
-            tracks power state of connectors. To use the function, drivers must
-            provide <methodname>dpms</methodname> helper operations for CRTCs
-            and encoders to apply the DPMS state to the device.
-          </para>
-          <para>
-            The mid-layer doesn't track the power state of CRTCs and encoders.
-            The <methodname>dpms</methodname> helper operations can thus be
-            called with a mode identical to the currently active mode.
-          </para>
-        </listitem>
-        <listitem>
-          <synopsis>int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
-                                            uint32_t maxX, uint32_t maxY);</synopsis>
-          <para>
-            The <function>drm_helper_probe_single_connector_modes</function> helper
-            function is a connector <methodname>fill_modes</methodname>
-            implementation that updates the connection status for the connector
-            and then retrieves a list of modes by calling the connector
-            <methodname>get_modes</methodname> helper operation.
-          </para>
-         <para>
-            If the helper operation returns no mode, and if the connector status
-            is connector_status_connected, standard VESA DMT modes up to
-            1024x768 are automatically added to the modes list by a call to
-            <function>drm_add_modes_noedid</function>.
-          </para>
-          <para>
-            The function then filters out modes larger than
-            <parameter>max_width</parameter> and <parameter>max_height</parameter>
-            if specified. It finally calls the optional connector
-            <methodname>mode_valid</methodname> helper operation for each mode in
-            the probed list to check whether the mode is valid for the connector.
-          </para>
-        </listitem>
-      </itemizedlist>
-    </sect2>
-    <sect2>
-      <title>CRTC Helper Operations</title>
+      <title>Legacy CRTC Helper Operations</title>
       <itemizedlist>
         <listitem id="drm-helper-crtc-mode-fixup">
           <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc,
@@ -2308,7 +2232,7 @@ void intel_crt_init(struct drm_device *dev)
 !Pinclude/drm/drm_modeset_helper_vtables.h overview
     </sect2>
     <sect2>
-      <title>Modeset Helper Functions Reference</title>
+      <title>Legacy CRTC/Modeset Helper Functions Reference</title>
 !Edrivers/gpu/drm/drm_crtc_helper.c
 !Pdrivers/gpu/drm/drm_crtc_helper.c overview
     </sect2>

drivers/gpu/drm/drm_crtc_helper.c

@@ -51,6 +51,11 @@
  * the same callbacks which drivers can use to e.g. restore the modeset
  * configuration on resume with drm_helper_resume_force_mode().
  *
+ * Note that this helper library doesn't track the current power state of CRTCs
+ * and encoders. It can call callbacks like ->dpms() even though the hardware is
+ * already in the desired state. This deficiency has been fixed in the atomic
+ * helpers.
+ *
  * The driver callbacks are mostly compatible with the atomic modeset helpers,
  * except for the handling of the primary plane: Atomic helpers require that the
  * primary plane is implemented as a real standalone plane and not directly tied
@@ -211,8 +216,8 @@ static void __drm_helper_disable_unused_functions(struct drm_device *dev)
  * @dev: DRM device
  *
  * This function walks through the entire mode setting configuration of @dev. It
- * will remove any crtc links of unused encoders and encoder links of
- * disconnected connectors. Then it will disable all unused encoders and crtcs
+ * will remove any CRTC links of unused encoders and encoder links of
+ * disconnected connectors. Then it will disable all unused encoders and CRTCs
  * either by calling their disable callback if available or by calling their
  * dpms callback with DRM_MODE_DPMS_OFF.
  */
@@ -450,11 +455,36 @@ drm_crtc_helper_disable(struct drm_crtc *crtc)
  * drm_crtc_helper_set_config - set a new config from userspace
  * @set: mode set configuration
  *
- * Setup a new configuration, provided by the upper layers (either an ioctl call
- * from userspace or internally e.g. from the fbdev support code) in @set, and
- * enable it. This is the main helper functions for drivers that implement
- * kernel mode setting with the crtc helper functions and the assorted
- * ->prepare(), ->modeset() and ->commit() helper callbacks.
+ * The drm_crtc_helper_set_config() helper function implements the set_config
+ * callback of struct &drm_crtc_funcs for drivers using the legacy CRTC helpers.
+ *
+ * It first tries to locate the best encoder for each connector by calling the
+ * connector ->best_encoder() (struct &drm_connector_helper_funcs) helper
+ * operation.
+ *
+ * After locating the appropriate encoders, the helper function will call the
+ * mode_fixup encoder and CRTC helper operations to adjust the requested mode,
+ * or reject it completely in which case an error will be returned to the
+ * application. If the new configuration after mode adjustment is identical to
+ * the current configuration the helper function will return without performing
+ * any other operation.
+ *
+ * If the adjusted mode is identical to the current mode but changes to the
+ * frame buffer need to be applied, the drm_crtc_helper_set_config() function
+ * will call the CRTC ->mode_set_base() (struct &drm_crtc_helper_funcs) helper
+ * operation.
+ *
+ * If the adjusted mode differs from the current mode, or if the
+ * ->mode_set_base() helper operation is not provided, the helper function
+ * performs a full mode set sequence by calling the ->prepare(), ->mode_set()
+ * and ->commit() CRTC and encoder helper operations, in that order.
+ * Alternatively it can also use the dpms and disable helper operations. For
+ * details see struct &drm_crtc_helper_funcs and struct
+ * &drm_encoder_helper_funcs.
+ *
+ * This function is deprecated.  New drivers must implement atomic modeset
+ * support, for which this function is unsuitable. Instead drivers should use
+ * drm_atomic_helper_set_config().
  *
  * Returns:
  * Returns 0 on success, negative errno numbers on failure.
@@ -763,10 +793,18 @@ static int drm_helper_choose_crtc_dpms(struct drm_crtc *crtc)
  * @connector: affected connector
  * @mode: DPMS mode
  *
- * This is the main helper function provided by the crtc helper framework for
+ * The drm_helper_connector_dpms() helper function implements the ->dpms()
+ * callback of struct &drm_connector_funcs for drivers using the legacy CRTC helpers.
+ *
+ * This is the main helper function provided by the CRTC helper framework for
  * implementing the DPMS connector attribute. It computes the new desired DPMS
- * state for all encoders and crtcs in the output mesh and calls the ->dpms()
- * callback provided by the driver appropriately.
+ * state for all encoders and CRTCs in the output mesh and calls the ->dpms()
+ * callbacks provided by the driver in struct &drm_crtc_helper_funcs and struct
+ * &drm_encoder_helper_funcs appropriately.
+ *
+ * This function is deprecated.  New drivers must implement atomic modeset
+ * support, for which this function is unsuitable. Instead drivers should use
+ * drm_atomic_helper_connector_dpms().
  *
  * Returns:
  * Always returns 0.
@@ -924,9 +962,9 @@ EXPORT_SYMBOL(drm_helper_resume_force_mode);
  * @old_fb: previous framebuffer
  *
  * This function implements a callback useable as the ->mode_set callback
- * required by the crtc helpers. Besides the atomic plane helper functions for
+ * required by the CRTC helpers. Besides the atomic plane helper functions for
  * the primary plane the driver must also provide the ->mode_set_nofb callback
- * to set up the crtc.
+ * to set up the CRTC.
  *
  * This is a transitional helper useful for converting drivers to the atomic
  * interfaces.
@@ -990,7 +1028,7 @@ EXPORT_SYMBOL(drm_helper_crtc_mode_set);
  * @old_fb: previous framebuffer
  *
  * This function implements a callback useable as the ->mode_set_base used
- * required by the crtc helpers. The driver must provide the atomic plane helper
+ * required by the CRTC helpers. The driver must provide the atomic plane helper
  * functions for the primary plane.
  *
  * This is a transitional helper useful for converting drivers to the atomic

drivers/gpu/drm/drm_probe_helper.c

@@ -273,15 +273,28 @@ prune:
  * @maxX: max width for modes
  * @maxY: max height for modes
  *
- * Based on the helper callbacks implemented by @connector try to detect all
- * valid modes.  Modes will first be added to the connector's probed_modes list,
- * then culled (based on validity and the @maxX, @maxY parameters) and put into
- * the normal modes list.
+ * Based on the helper callbacks implemented by @connector in struct
+ * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
+ * be added to the connector's probed_modes list, then culled (based on validity
+ * and the @maxX, @maxY parameters) and put into the normal modes list.
  *
- * Intended to be use as a generic implementation of the ->fill_modes()
- * @connector vfunc for drivers that use the crtc helpers for output mode
+ * Intended to be used as a generic implementation of the ->fill_modes()
+ * @connector vfunc for drivers that use the CRTC helpers for output mode
  * filtering and detection.
  *
+ * If the helper operation returns no mode, and if the connector status is
+ * connector_status_connected, standard VESA DMT modes up to 1024x768 are
+ * automatically added to the modes list by a call to
+ * drm_add_modes_noedid().
+ *
+ * The function then filters out modes larger than @maxX and maxY if specified.
+ * It finally calls the optional connector ->mode_valid() helper operation for each
+ * mode in the probed list to check whether the mode is valid for the connector.
+ *
+ * Compared to drm_helper_probe_single_connector_modes_nomerge() this function
+ * merged the mode bits for the preferred mode, as a hack to work around some
+ * quirky issues on funky hardware.
+ *
  * Returns:
  * The number of modes found on @connector.
  */
@@ -298,8 +311,11 @@ EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
  * @maxX: max width for modes
  * @maxY: max height for modes
  *
- * This operates like drm_hehlper_probe_single_connector_modes except it
+ * This operates like drm_hehlper_probe_single_connector_modes() except it
  * replaces the mode bits instead of merging them for preferred modes.
+ *
+ * Returns:
+ * The number of modes found on @connector.
  */
 int drm_helper_probe_single_connector_modes_nomerge(struct drm_connector *connector,
 					    uint32_t maxX, uint32_t maxY)