drm/imx: Add active plane reconfiguration support

We don't support configuring active plane on-the-fly for imx-drm.
The relevant CRTC should be disabled before the plane configuration.
Of course, the plane itself should be disabled as well.

This patch adds active plane reconfiguration support by forcing CRTC
mode change in plane's ->atomic_check callback so that the CRTC
will be disabled before the plane configuration.
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Liu Ying <gnuiyl@gmail.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/imx-drm-core.c

@@ -146,10 +146,34 @@ static void imx_drm_output_poll_changed(struct drm_device *drm)
 	drm_fbdev_cma_hotplug_event(imxdrm->fbhelper);
 }
 
+static int imx_drm_atomic_check(struct drm_device *dev,
+				struct drm_atomic_state *state)
+{
+	int ret;
+
+	ret = drm_atomic_helper_check_modeset(dev, state);
+	if (ret)
+		return ret;
+
+	ret = drm_atomic_helper_check_planes(dev, state);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check modeset again in case crtc_state->mode_changed is
+	 * updated in plane's ->atomic_check callback.
+	 */
+	ret = drm_atomic_helper_check_modeset(dev, state);
+	if (ret)
+		return ret;
+
+	return ret;
+}
+
 static const struct drm_mode_config_funcs imx_drm_mode_config_funcs = {
 	.fb_create = drm_fb_cma_create,
 	.output_poll_changed = imx_drm_output_poll_changed,
-	.atomic_check = drm_atomic_helper_check,
+	.atomic_check = imx_drm_atomic_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };
 

drivers/gpu/drm/imx/ipuv3-plane.c

@@ -319,13 +319,16 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
 		return -EINVAL;
 
 	/*
-	 * since we cannot touch active IDMAC channels, we do not support
-	 * resizing the enabled plane or changing its format
+	 * We support resizing active plane or changing its format by
+	 * forcing CRTC mode change in plane's ->atomic_check callback
+	 * and disabling all affected active planes in CRTC's ->atomic_disable
+	 * callback.  The planes will be reenabled in plane's ->atomic_update
+	 * callback.
 	 */
 	if (old_fb && (state->src_w != old_state->src_w ||
 			      state->src_h != old_state->src_h ||
 			      fb->pixel_format != old_fb->pixel_format))
-		return -EINVAL;
+		crtc_state->mode_changed = true;
 
 	eba = drm_plane_state_to_eba(state);
 
@@ -336,7 +339,7 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
 		return -EINVAL;
 
 	if (old_fb && fb->pitches[0] != old_fb->pitches[0])
-		return -EINVAL;
+		crtc_state->mode_changed = true;
 
 	switch (fb->pixel_format) {
 	case DRM_FORMAT_YUV420:
@@ -372,7 +375,7 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
 			return -EINVAL;
 
 		if (old_fb && old_fb->pitches[1] != fb->pitches[1])
-			return -EINVAL;
+			crtc_state->mode_changed = true;
 	}
 
 	return 0;