[PATCH v2 01/21] drm: Add get_scanout_position() to struct drm_crtc_helper_funcs

[Thomas Zimmermann <tzimmermann@suse.de>]

The new callback get_scanout_position() reads the current location of
the scanout process. The operation is currentyl located in struct
drm_driver, but really belongs to the CRTC. Drivers will be converted
in separate patches.

v2:
	* fix logical op in drm_calc_vbltimestamp_from_scanoutpos()

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Yannick Fertré <yannick.fertre@st.com>
---
 drivers/gpu/drm/drm_vblank.c             | 24 ++++++++----
 include/drm/drm_drv.h                    |  7 +---
 include/drm/drm_modeset_helper_vtables.h | 47 ++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 1659b13b178c..3f1dd54cc8bb 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -30,6 +30,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_framebuffer.h>
+#include <drm/drm_modeset_helper_vtables.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 
@@ -590,7 +591,7 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants);
  * Implements calculation of exact vblank timestamps from given drm_display_mode
  * timings and current video scanout position of a CRTC. This can be directly
  * used as the &drm_driver.get_vblank_timestamp implementation of a kms driver
- * if &drm_driver.get_scanout_position is implemented.
+ * if &drm_crtc_helper_funcs.get_scanout_position is implemented.
  *
  * The current implementation only handles standard video modes. For double scan
  * and interlaced modes the driver is supposed to adjust the hardware mode
@@ -632,8 +633,9 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 	}
 
 	/* Scanout position query not supported? Should not happen. */
-	if (!dev->driver->get_scanout_position) {
-		DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
+	if (!dev->driver->get_scanout_position &&
+	    !crtc->helper_private->get_scanout_position) {
+		DRM_ERROR("Called from CRTC w/o get_scanout_position()!?\n");
 		return false;
 	}
 
@@ -664,11 +666,17 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 		 * Get vertical and horizontal scanout position vpos, hpos,
 		 * and bounding timestamps stime, etime, pre/post query.
 		 */
-		vbl_status = dev->driver->get_scanout_position(dev, pipe,
-							       in_vblank_irq,
-							       &vpos, &hpos,
-							       &stime, &etime,
-							       mode);
+		if (crtc->helper_private->get_scanout_position) {
+			vbl_status =
+				crtc->helper_private->get_scanout_position(
+					crtc, in_vblank_irq, &vpos, &hpos,
+					&stime, &etime, mode);
+		} else {
+			vbl_status =
+				dev->driver->get_scanout_position(
+					dev, pipe, in_vblank_irq, &vpos,
+					&hpos, &stime, &etime, mode);
+		}
 
 		/* Return as no-op if scanout query unsupported or failed. */
 		if (!vbl_status) {
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index cf13470810a5..d0049e5786fc 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -362,11 +362,8 @@ struct drm_driver {
 	 * True on success, false if a reliable scanout position counter could
 	 * not be read out.
 	 *
-	 * FIXME:
-	 *
-	 * Since this is a helper to implement @get_vblank_timestamp, we should
-	 * move it to &struct drm_crtc_helper_funcs, like all the other
-	 * helper-internal hooks.
+	 * This is deprecated and should not be used by new drivers.
+	 * Use &drm_crtc_helper_funcs.get_scanout_position instead.
 	 */
 	bool (*get_scanout_position) (struct drm_device *dev, unsigned int pipe,
 				      bool in_vblank_irq, int *vpos, int *hpos,
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 5a87f1bd7a3f..e398512bfd5f 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -450,6 +450,53 @@ struct drm_crtc_helper_funcs {
 	 */
 	void (*atomic_disable)(struct drm_crtc *crtc,
 			       struct drm_crtc_state *old_crtc_state);
+
+	/**
+	 * @get_scanout_position:
+	 *
+	 * Called by vblank timestamping code.
+	 *
+	 * Returns the current display scanout position from a CRTC and an
+	 * optional accurate ktime_get() timestamp of when the position was
+	 * measured. Note that this is a helper callback which is only used
+	 * if a driver uses drm_calc_vbltimestamp_from_scanoutpos() for the
+	 * @drm_driver.get_vblank_timestamp callback.
+	 *
+	 * Parameters:
+	 *
+	 * crtc:
+	 *     The CRTC.
+	 * in_vblank_irq:
+	 *     True when called from drm_crtc_handle_vblank(). Some drivers
+	 *     need to apply some workarounds for gpu-specific vblank irq
+	 *     quirks if the flag is set.
+	 * vpos:
+	 *     Target location for current vertical scanout position.
+	 * hpos:
+	 *     Target location for current horizontal scanout position.
+	 * stime:
+	 *     Target location for timestamp taken immediately before
+	 *     scanout position query. Can be NULL to skip timestamp.
+	 * etime:
+	 *     Target location for timestamp taken immediately after
+	 *     scanout position query. Can be NULL to skip timestamp.
+	 * mode:
+	 *     Current display timings.
+	 *
+	 * Returns vpos as a positive number while in active scanout area.
+	 * Returns vpos as a negative number inside vblank, counting the number
+	 * of scanlines to go until end of vblank, e.g., -1 means "one scanline
+	 * until start of active scanout / end of vblank."
+	 *
+	 * Returns:
+	 *
+	 * True on success, false if a reliable scanout position counter could
+	 * not be read out.
+	 */
+	bool (*get_scanout_position)(struct drm_crtc *crtc,
+				     bool in_vblank_irq, int *vpos, int *hpos,
+				     ktime_t *stime, ktime_t *etime,
+				     const struct drm_display_mode *mode);
 };
 
 /**
-- 
2.24.1