pointer to CRTC functions.
</para>
</sect3>
- <sect3 id="drm-kms-crtcops">
- <title>CRTC Operations</title>
- <sect4>
- <title>Set Configuration</title>
- <synopsis>int (*set_config)(struct drm_mode_set *set);</synopsis>
- <para>
- Apply a new CRTC configuration to the device. The configuration
- specifies a CRTC, a frame buffer to scan out from, a (x,y) position in
- the frame buffer, a display mode and an array of connectors to drive
- with the CRTC if possible.
- </para>
- <para>
- If the frame buffer specified in the configuration is NULL, the driver
- must detach all encoders connected to the CRTC and all connectors
- attached to those encoders and disable them.
- </para>
- <para>
- This operation is called with the mode config lock held.
- </para>
- <note><para>
- Note that the drm core has no notion of restoring the mode setting
- state after resume, since all resume handling is in the full
- responsibility of the driver. The common mode setting helper library
- though provides a helper which can be used for this:
- <function>drm_helper_resume_force_mode</function>.
- </para></note>
- </sect4>
- <sect4>
- <title>Page Flipping</title>
- <synopsis>int (*page_flip)(struct drm_crtc *crtc, struct drm_framebuffer *fb,
- struct drm_pending_vblank_event *event);</synopsis>
- <para>
- Schedule a page flip to the given frame buffer for the CRTC. This
- operation is called with the mode config mutex held.
- </para>
- <para>
- Page flipping is a synchronization mechanism that replaces the frame
- buffer being scanned out by the CRTC with a new frame buffer during
- vertical blanking, avoiding tearing. When an application requests a page
- flip the DRM core verifies that the new frame buffer is large enough to
- be scanned out by the CRTC in the currently configured mode and then
- calls the CRTC <methodname>page_flip</methodname> operation with a
- pointer to the new frame buffer.
- </para>
- <para>
- The <methodname>page_flip</methodname> operation schedules a page flip.
- Once any pending rendering targeting the new frame buffer has
- completed, the CRTC will be reprogrammed to display that frame buffer
- after the next vertical refresh. The operation must return immediately
- without waiting for rendering or page flip to complete and must block
- any new rendering to the frame buffer until the page flip completes.
- </para>
- <para>
- If a page flip can be successfully scheduled the driver must set the
- <code>drm_crtc->fb</code> field to the new framebuffer pointed to
- by <code>fb</code>. This is important so that the reference counting
- on framebuffers stays balanced.
- </para>
- <para>
- If a page flip is already pending, the
- <methodname>page_flip</methodname> operation must return
- -<errorname>EBUSY</errorname>.
- </para>
- <para>
- To synchronize page flip to vertical blanking the driver will likely
- need to enable vertical blanking interrupts. It should call
- <function>drm_vblank_get</function> for that purpose, and call
- <function>drm_vblank_put</function> after the page flip completes.
- </para>
- <para>
- If the application has requested to be notified when page flip completes
- the <methodname>page_flip</methodname> operation will be called with a
- non-NULL <parameter>event</parameter> argument pointing to a
- <structname>drm_pending_vblank_event</structname> instance. Upon page
- flip completion the driver must call <methodname>drm_send_vblank_event</methodname>
- to fill in the event and send to wake up any waiting processes.
- This can be performed with
- <programlisting><![CDATA[
- spin_lock_irqsave(&dev->event_lock, flags);
- ...
- drm_send_vblank_event(dev, pipe, event);
- spin_unlock_irqrestore(&dev->event_lock, flags);
- ]]></programlisting>
- </para>
- <note><para>
- FIXME: Could drivers that don't need to wait for rendering to complete
- just add the event to <literal>dev->vblank_event_list</literal> and
- let the DRM core handle everything, as for "normal" vertical blanking
- events?
- </para></note>
- <para>
- While waiting for the page flip to complete, the
- <literal>event->base.link</literal> list head can be used freely by
- the driver to store the pending event in a driver-specific list.
- </para>
- <para>
- If the file handle is closed before the event is signaled, drivers must
- take care to destroy the event in their
- <methodname>preclose</methodname> operation (and, if needed, call
- <function>drm_vblank_put</function>).
- </para>
- </sect4>
- <sect4>
- <title>Miscellaneous</title>
- <itemizedlist>
- <listitem>
- <synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
- uint32_t start, uint32_t size);</synopsis>
- <para>
- Apply a gamma table to the device. The operation is optional.
- </para>
- </listitem>
- </itemizedlist>
- </sect4>
- </sect3>
</sect2>
<sect2>
<title>Planes (struct <structname>drm_plane</structname>)</title>
<listitem>
DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary
planes are the planes operated upon by CRTC modesetting and flipping
- operations described in <xref linkend="drm-kms-crtcops"/>.
+ operations described in the page_flip hook in <structname>drm_crtc_funcs</structname>.
</listitem>
<listitem>
DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor
/**
* struct drm_crtc_funcs - control CRTCs for a given device
- * @cursor_set: setup the cursor
- * @cursor_set2: setup the cursor with hotspot, superseeds @cursor_set if set
- * @cursor_move: move the cursor
- * @gamma_set: specify color ramp for CRTC
- * @set_config: apply a new CRTC configuration
- * @page_flip: initiate a page flip
*
* The drm_crtc_funcs structure is the central CRTC management structure
* in the DRM. Each CRTC controls one or more connectors (note that the name
*/
void (*reset)(struct drm_crtc *crtc);
- /* cursor controls */
+ /**
+ * @cursor_set:
+ *
+ * Update the cursor image. The cursor position is relative to the CRTC
+ * and can be partially or fully outside of the visible area.
+ *
+ * Note that contrary to all other KMS functions the legacy cursor entry
+ * points don't take a framebuffer object, but instead take directly a
+ * raw buffer object id from the driver's buffer manager (which is
+ * either GEM or TTM for current drivers).
+ *
+ * This entry point is deprecated, drivers should instead implement
+ * universal plane support and register a proper cursor plane using
+ * drm_crtc_init_with_planes().
+ *
+ * This callback is optional
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure.
+ */
int (*cursor_set)(struct drm_crtc *crtc, struct drm_file *file_priv,
uint32_t handle, uint32_t width, uint32_t height);
+
+ /**
+ * @cursor_set2:
+ *
+ * Update the cursor image, including hotspot information. The hotspot
+ * must not affect the cursor position in CRTC coordinates, but is only
+ * meant as a hint for virtualized display hardware to coordinate the
+ * guests and hosts cursor position. The cursor hotspot is relative to
+ * the cursor image. Otherwise this works exactly like @cursor_set.
+ *
+ * This entry point is deprecated, drivers should instead implement
+ * universal plane support and register a proper cursor plane using
+ * drm_crtc_init_with_planes().
+ *
+ * This callback is optional.
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure.
+ */
int (*cursor_set2)(struct drm_crtc *crtc, struct drm_file *file_priv,
uint32_t handle, uint32_t width, uint32_t height,
int32_t hot_x, int32_t hot_y);
+
+ /**
+ * @cursor_move:
+ *
+ * Update the cursor position. The cursor does not need to be visible
+ * when this hook is called.
+ *
+ * This entry point is deprecated, drivers should instead implement
+ * universal plane support and register a proper cursor plane using
+ * drm_crtc_init_with_planes().
+ *
+ * This callback is optional.
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure.
+ */
int (*cursor_move)(struct drm_crtc *crtc, int x, int y);
- /* Set gamma on the CRTC */
+ /**
+ * @gamma_set:
+ *
+ * Set gamma on the CRTC.
+ *
+ * This callback is optional.
+ *
+ * NOTE:
+ *
+ * Drivers that support gamma tables and also fbdev emulation through
+ * the provided helper library need to take care to fill out the gamma
+ * hooks for both. Currently there's a bit an unfortunate duplication
+ * going on, which should eventually be unified to just one set of
+ * hooks.
+ */
void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
uint32_t start, uint32_t size);
*/
void (*destroy)(struct drm_crtc *crtc);
+ /**
+ * @set_config:
+ *
+ * This is the main legacy entry point to change the modeset state on a
+ * CRTC. All the details of the desired configuration are passed in a
+ * struct &drm_mode_set - see there for details.
+ *
+ * Drivers implementing atomic modeset should use
+ * drm_atomic_helper_set_config() to implement this hook.
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure.
+ */
int (*set_config)(struct drm_mode_set *set);
- /*
- * Flip to the given framebuffer. This implements the page
- * flip ioctl described in drm_mode.h, specifically, the
- * implementation must return immediately and block all
- * rendering to the current fb until the flip has completed.
- * If userspace set the event flag in the ioctl, the event
- * argument will point to an event to send back when the flip
- * completes, otherwise it will be NULL.
+ /**
+ * @page_flip:
+ *
+ * Legacy entry point to schedule a flip to the given framebuffer.
+ *
+ * Page flipping is a synchronization mechanism that replaces the frame
+ * buffer being scanned out by the CRTC with a new frame buffer during
+ * vertical blanking, avoiding tearing (except when requested otherwise
+ * through the DRM_MODE_PAGE_FLIP_ASYNC flag). When an application
+ * requests a page flip the DRM core verifies that the new frame buffer
+ * is large enough to be scanned out by the CRTC in the currently
+ * configured mode and then calls the CRTC ->page_flip() operation with a
+ * pointer to the new frame buffer.
+ *
+ * The driver must wait for any pending rendering to the new framebuffer
+ * to complete before executing the flip. It should also wait for any
+ * pending rendering from other drivers if the underlying buffer is a
+ * shared dma-buf.
+ *
+ * An application can request to be notified when the page flip has
+ * completed. The drm core will supply a struct &drm_event in the event
+ * parameter in this case. This can be handled by the
+ * drm_crtc_send_vblank_event() function, which the driver should call on
+ * the provided event upon completion of the flip. Note that if
+ * the driver supports vblank signalling and timestamping the vblank
+ * counters and timestamps must agree with the ones returned from page
+ * flip events. With the current vblank helper infrastructure this can
+ * be achieved by holding a vblank reference while the page flip is
+ * pending, acquired through drm_crtc_vblank_get() and released with
+ * drm_crtc_vblank_put(). Drivers are free to implement their own vblank
+ * counter and timestamp tracking though, e.g. if they have accurate
+ * timestamp registers in hardware.
+ *
+ * FIXME:
+ *
+ * Up to that point drivers need to manage events themselves and can use
+ * even->base.list freely for that. Specifically they need to ensure
+ * that they don't send out page flip (or vblank) events for which the
+ * corresponding drm file has been closed already. The drm core
+ * unfortunately does not (yet) take care of that. Therefore drivers
+ * currently must clean up and release pending events in their
+ * ->preclose driver function.
+ *
+ * This callback is optional.
+ *
+ * NOTE:
+ *
+ * Very early versions of the KMS ABI mandated that the driver must
+ * block (but not reject) any rendering to the old framebuffer until the
+ * flip operation has completed and the old framebuffer is no longer
+ * visible. This requirement has been lifted, and userspace is instead
+ * expected to request delivery of an event and wait with recycling old
+ * buffers until such has been received.
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure. Note that if a
+ * ->page_flip() operation is already pending the callback should return
+ * -EBUSY. Pageflips on a disabled CRTC (either by setting a NULL mode
+ * or just runtime disabled through DPMS respectively the new atomic
+ * "ACTIVE" state) should result in an -EINVAL error code.
*/
int (*page_flip)(struct drm_crtc *crtc,
struct drm_framebuffer *fb,
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