The hardware requires the HDSR and VDSR registers to be set to 1 or higher. This translates to a minimum combined horizontal sync and back porch of 20 pixels and a minimum vertical back porch of 3 lines. Reject modes that fail those requirements. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> --- Changes since v1: - Don't use mode->crtc_v* as they are only set after calling .mode_valid() - Tested the patch on real hardware (which would have prevented the buggy v1...) --- drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c index 79021d7aa3ce..90dacab67be5 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c @@ -735,10 +735,22 @@ enum drm_mode_status rcar_du_crtc_mode_valid(struct drm_crtc *crtc, struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc); struct rcar_du_device *rcdu = rcrtc->group->dev; bool interlaced = mode->flags & DRM_MODE_FLAG_INTERLACE; + unsigned int vbp; if (interlaced && !rcar_du_has(rcdu, RCAR_DU_FEATURE_INTERLACED)) return MODE_NO_INTERLACE; + /* + * The hardware requires a minimum combined horizontal sync and back + * porch of 20 pixels and a minimum vertical back porch of 3 lines. + */ + if (mode->htotal - mode->hsync_start < 20) + return MODE_HBLANK_NARROW; + + vbp = (mode->vtotal - mode->vsync_end) / (interlaced ? 2 : 1); + if (vbp < 3) + return MODE_VBLANK_NARROW; + return MODE_OK; } -- Regards, Laurent Pinchart
