[PATCH 3/3] drm/amd/display: size frame-packed streams by the doubled timing

[Adrian Betschart <adrian.betschart@cinemaone.ch>]

A frame-packed 3D mode scans out both views and the active space
between them in one frame, so the CRTC is 2205 lines tall for a
1080p mode. The stream scaling code took the source height from
mode->vdisplay (1080) against the 2205-line addressable destination;
with aspect scaling that keeps 1080 lines and centres them, so the
first view is stretched across both eye windows and the second view
is never shown. The plane viewport check clipped planes to
crtc_vdisplay for the same reason.

Use drm_mode_get_hv_timing(), which returns the doubled height for
stereo modes and the plain display size otherwise, in both places.

Measured on a Radeon RX 7600 with a frame-packed 1920x1080p24 mode:
before, a row-coded 2205-line test frame showed rows of the first
view in both eyes; after, each eye receives its own view.

Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
---
 .../drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c | 11 ++++++++---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c | 13 +++++++++----
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
index 7a2beb175..ac9fe2883 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_connector.c
@@ -1405,9 +1405,14 @@ void amdgpu_dm_update_stream_scaling_settings(struct drm_device *dev,
 	if (!mode)
 		return;
 
-	/* Full screen scaling by default */
-	src.width = mode->hdisplay;
-	src.height = mode->vdisplay;
+	/*
+	 * Full screen scaling by default. A frame-packed 3D mode scans out the
+	 * doubled timing, so the source size is the CRTC size, not vdisplay:
+	 * with 1080 lines against a 2205-line destination the aspect fit would
+	 * keep 1080 lines and centre them, putting the first view across both
+	 * eye windows and none of the second.
+	 */
+	drm_mode_get_hv_timing(mode, &src.width, &src.height);
 	dst.width = stream->timing.h_addressable;
 	dst.height = stream->timing.v_addressable;
 
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index 0a5a73472..8db656ef8 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -1407,16 +1407,21 @@ int amdgpu_dm_plane_helper_check_state(struct drm_plane_state *state,
 		if (state->plane->type != DRM_PLANE_TYPE_CURSOR) {
 			int viewport_width = state->crtc_w;
 			int viewport_height = state->crtc_h;
+			int mode_hdisplay, mode_vdisplay;
+
+			/* frame-packed 3D scans out the doubled timing */
+			drm_mode_get_hv_timing(&new_crtc_state->mode,
+					       &mode_hdisplay, &mode_vdisplay);
 
 			if (state->crtc_x < 0)
 				viewport_width += state->crtc_x;
-			else if (state->crtc_x + state->crtc_w > new_crtc_state->mode.crtc_hdisplay)
-				viewport_width = new_crtc_state->mode.crtc_hdisplay - state->crtc_x;
+			else if (state->crtc_x + state->crtc_w > mode_hdisplay)
+				viewport_width = mode_hdisplay - state->crtc_x;
 
 			if (state->crtc_y < 0)
 				viewport_height += state->crtc_y;
-			else if (state->crtc_y + state->crtc_h > new_crtc_state->mode.crtc_vdisplay)
-				viewport_height = new_crtc_state->mode.crtc_vdisplay - state->crtc_y;
+			else if (state->crtc_y + state->crtc_h > mode_vdisplay)
+				viewport_height = mode_vdisplay - state->crtc_y;
 
 			if (viewport_width < 0 || viewport_height < 0) {
 				DRM_DEBUG_ATOMIC("Plane completely outside of screen\n");
-- 
2.43.0