Previously center scaling would get scaling applied to it (when it was only supposed to center the image), and aspect-corrected scaling did not always correctly pick whether to reduce width or height for a particular combination of inputs/outputs.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110660 Signed-off-by: Ilia Mirkin imirkin@alum.mit.edu ---
Tested on a 1920x1200-native screen with a 640x480 mode (got letter boxes on the side) and 720x400 mode (got letter boxes on top/bottom).
drivers/gpu/drm/nouveau/dispnv50/head.c | 28 +++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/dispnv50/head.c b/drivers/gpu/drm/nouveau/dispnv50/head.c index ac97ebce5b35..e2207990d3cc 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/head.c +++ b/drivers/gpu/drm/nouveau/dispnv50/head.c @@ -169,14 +169,34 @@ nv50_head_atomic_check_view(struct nv50_head_atom *armh, */ switch (mode) { case DRM_MODE_SCALE_CENTER: - asyh->view.oW = min((u16)umode->hdisplay, asyh->view.oW); - asyh->view.oH = min((u16)umode_vdisplay, asyh->view.oH); - /* fall-through */ + /* NOTE: This will cause scaling when the input is + * larger than the output. + */ + asyh->view.oW = min(asyh->view.iW, asyh->view.oW); + asyh->view.oH = min(asyh->view.iH, asyh->view.oH); + break; case DRM_MODE_SCALE_ASPECT: - if (asyh->view.oH < asyh->view.oW) { + /* Determine whether the scaling should be on width or on + * height. This is done by comparing the aspect ratios of the + * sizes. If the output AR is larger than input AR, that means + * we want to change the width (letterboxed on the + * left/right), otherwise on the height (letterboxed on the + * top/bottom). + * + * E.g. 4:3 (1.333) AR image displayed on a 16:10 (1.6) AR + * screen will have letterboxes on the left/right. However a + * 16:9 (1.777) AR image on that same screen will have + * letterboxes on the top/bottom. + * + * inputAR = iW / iH; outputAR = oW / oH + * outputAR > inputAR is equivalent to oW * iH > iW * oH + */ + if (asyh->view.oW * asyh->view.iH > asyh->view.iW * asyh->view.oH) { + /* Recompute output width, i.e. left/right letterbox */ u32 r = (asyh->view.iW << 19) / asyh->view.iH; asyh->view.oW = ((asyh->view.oH * r) + (r / 2)) >> 19; } else { + /* Recompute output height, i.e. top/bottom letterbox */ u32 r = (asyh->view.iH << 19) / asyh->view.iW; asyh->view.oH = ((asyh->view.oW * r) + (r / 2)) >> 19; }