drm/crtc-helper: Transitional functions using atomic plane helpers

These two functions allow drivers to reuse their atomic plane helpers
functions for the primary plane to implement the interfaces required
by the crtc helpers for the legacy ->set_config callback.

This is purely transitional and won't be used once the driver is fully
converted. But it allows partial conversions to the atomic plane
helpers which are functional.

v2:
- Use ->atomic_duplicate_state if available.
- Don't forget to run crtc_funcs->atomic_check.

v3: Shift source coordinates correctly for 16.16 fixed point.

v4: Don't forget to call ->atomic_destroy_state if available.

v5: Fixup kerneldoc.

v6: Reuse the plane_commit function from the transitional plane
helpers to avoid too much duplication.

v7:
- Remove some stale comment.
- Correctly handle the lack of plane->state object, necessary for
transitional use.

v8: Fixup an embarrassing h/vdisplay mixup.

Reviewed-by: Sean Paul <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/drm_crtc_helper.c

···
 #include <drm/drm_fourcc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_plane_helper.h>
 #include <drm/drm_edid.h>
 
 MODULE_AUTHOR("David Airlie, Jesse Barnes");
···
 	drm_modeset_unlock_all(dev);
 }
 EXPORT_SYMBOL(drm_helper_resume_force_mode);
+
+/**
+ * drm_helper_crtc_mode_set - mode_set implementation for atomic plane helpers
+ * @crtc: DRM CRTC
+ * @mode: DRM display mode which userspace requested
+ * @adjusted_mode: DRM display mode adjusted by ->mode_fixup callbacks
+ * @x: x offset of the CRTC scanout area on the underlying framebuffer
+ * @y: y offset of the CRTC scanout area on the underlying framebuffer
+ * @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
+ * the primary plane the driver must also provide the ->mode_set_nofb callback
+ * to set up the crtc.
+ *
+ * This is a transitional helper useful for converting drivers to the atomic
+ * interfaces.
+ */
+int drm_helper_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode,
+			     struct drm_display_mode *adjusted_mode, int x, int y,
+			     struct drm_framebuffer *old_fb)
+{
+	struct drm_crtc_state *crtc_state;
+	struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+	int ret;
+
+	if (crtc->funcs->atomic_duplicate_state)
+		crtc_state = crtc->funcs->atomic_duplicate_state(crtc);
+	else if (crtc->state)
+		crtc_state = kmemdup(crtc->state, sizeof(*crtc_state),
+				     GFP_KERNEL);
+	else
+		crtc_state = kzalloc(sizeof(*crtc_state), GFP_KERNEL);
+	if (!crtc_state)
+		return -ENOMEM;
+
+	crtc_state->enable = true;
+	crtc_state->planes_changed = true;
+	drm_mode_copy(&crtc_state->mode, mode);
+	drm_mode_copy(&crtc_state->adjusted_mode, adjusted_mode);
+
+	if (crtc_funcs->atomic_check) {
+		ret = crtc_funcs->atomic_check(crtc, crtc_state);
+		if (ret) {
+			kfree(crtc_state);
+
+			return ret;
+		}
+	}
+
+	swap(crtc->state, crtc_state);
+
+	crtc_funcs->mode_set_nofb(crtc);
+
+	if (crtc_state) {
+		if (crtc->funcs->atomic_destroy_state)
+			crtc->funcs->atomic_destroy_state(crtc, crtc_state);
+		else
+			kfree(crtc_state);
+	}
+
+	return drm_helper_crtc_mode_set_base(crtc, x, y, old_fb);
+}
+EXPORT_SYMBOL(drm_helper_crtc_mode_set);
+
+/**
+ * drm_helper_crtc_mode_set_base - mode_set_base implementation for atomic plane helpers
+ * @crtc: DRM CRTC
+ * @x: x offset of the CRTC scanout area on the underlying framebuffer
+ * @y: y offset of the CRTC scanout area on the underlying framebuffer
+ * @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
+ * functions for the primary plane.
+ *
+ * This is a transitional helper useful for converting drivers to the atomic
+ * interfaces.
+ */
+int drm_helper_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
+				  struct drm_framebuffer *old_fb)
+{
+	struct drm_plane_state *plane_state;
+	struct drm_plane *plane = crtc->primary;
+
+	if (plane->funcs->atomic_duplicate_state)
+		plane_state = plane->funcs->atomic_duplicate_state(plane);
+	else if (plane->state)
+		plane_state = kmemdup(plane->state, sizeof(*plane_state),
+				      GFP_KERNEL);
+	else
+		plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
+	if (!plane_state)
+		return -ENOMEM;
+
+	plane_state->crtc = crtc;
+	plane_state->fb = crtc->primary->fb;
+	plane_state->crtc_x = 0;
+	plane_state->crtc_y = 0;
+	plane_state->crtc_h = crtc->mode.vdisplay;
+	plane_state->crtc_w = crtc->mode.hdisplay;
+	plane_state->src_x = x << 16;
+	plane_state->src_y = y << 16;
+	plane_state->src_h = crtc->mode.vdisplay << 16;
+	plane_state->src_w = crtc->mode.hdisplay << 16;
+
+	return drm_plane_helper_commit(plane, plane_state, old_fb);
+}
+EXPORT_SYMBOL(drm_helper_crtc_mode_set_base);

drivers/gpu/drm/drm_plane_helper.c

···
 }
 EXPORT_SYMBOL(drm_crtc_init);
 
-static int
-plane_commit(struct drm_plane *plane, struct drm_plane_state *plane_state,
-	     struct drm_framebuffer *old_fb)
+int drm_plane_helper_commit(struct drm_plane *plane,
+			    struct drm_plane_state *plane_state,
+			    struct drm_framebuffer *old_fb)
 {
 	struct drm_plane_helper_funcs *plane_funcs;
 	struct drm_crtc *crtc[2];
···
 	plane_state->src_h = src_h;
 	plane_state->src_w = src_w;
 
-	return plane_commit(plane, plane_state, plane->fb);
+	return drm_plane_helper_commit(plane, plane_state, plane->fb);
 }
 EXPORT_SYMBOL(drm_plane_helper_update);
 
···
 	plane_state->crtc = NULL;
 	plane_state->fb = NULL;
 
-	return plane_commit(plane, plane_state, plane->fb);
+	return drm_plane_helper_commit(plane, plane_state, plane->fb);
 }
 EXPORT_SYMBOL(drm_plane_helper_disable);

include/drm/drm_crtc.h

···
  * struct drm_crtc_state - mutable CRTC state
  * @enable: whether the CRTC should be enabled, gates all other state
  * @planes_changed: for use by helpers and drivers when computing state updates
+ * @adjusted_mode: for use by helpers and drivers to compute adjusted mode timings
  * @mode: current mode timings
  * @event: optional pointer to a DRM event to signal upon completion of the
  * 	state update
···
 
 	/* computed state bits used by helpers and drivers */
 	bool planes_changed : 1;
+
+	/* adjusted_mode: for use by helpers and drivers */
+	struct drm_display_mode adjusted_mode;
 
 	struct drm_display_mode mode;
 

include/drm/drm_crtc_helper.h

···
 	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
 			struct drm_display_mode *adjusted_mode, int x, int y,
 			struct drm_framebuffer *old_fb);
+	void (*mode_set_nofb)(struct drm_crtc *crtc);
 
 	/* Move the crtc on the current fb to the given position *optional* */
 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
···
 }
 
 extern void drm_helper_resume_force_mode(struct drm_device *dev);
+
+int drm_helper_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode,
+			     struct drm_display_mode *adjusted_mode, int x, int y,
+			     struct drm_framebuffer *old_fb);
+int drm_helper_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
+				  struct drm_framebuffer *old_fb);
 
 /* drm_probe_helper.c */
 extern int drm_helper_probe_single_connector_modes(struct drm_connector

include/drm/drm_plane_helper.h

···
 			    uint32_t src_w, uint32_t src_h);
 int drm_plane_helper_disable(struct drm_plane *plane);
 
+/* For use by drm_crtc_helper.c */
+int drm_plane_helper_commit(struct drm_plane *plane,
+			    struct drm_plane_state *plane_state,
+			    struct drm_framebuffer *old_fb);
 #endif