[PATCH 15/36] drm/i915: Reject cloning when using pfit

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

The panel fitter lives inside the pipe and so would affect all cloned
outputs. However the relevant properties (scaling mode, TV margins) are
per-connector so we could end up with a situation where each cloned
output wants a different pfit configuration. Let's just reject pfit
usage with cloning entirely.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_panel.c | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 9c7d070c286a..d6028303b16f 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -258,6 +258,26 @@ static int intel_pch_pfit_check_timings(const struct intel_crtc_state *crtc_stat
 	return 0;
 }
 
+static int intel_pch_pfit_check_cloning(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+
+	/*
+	 * The panel fitter is in the pipe and thus would affect every
+	 * cloned output. The relevant properties (scaling mode, TV
+	 * margins) are per-connector so we'd have to make sure each
+	 * output sets them up identically. Seems like a very niche use
+	 * case so let's just reject cloning entirely when pfit is used.
+	 */
+	if (!is_power_of_2(crtc_state->output_types)) {
+		DRM_DEBUG_KMS("[CRTC:%d:%s] no pfit when cloning\n",
+			      crtc->base.base.id, crtc->base.name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* adjusted_mode has been preset to be the panel's fixed mode */
 int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
 			    const struct drm_connector_state *conn_state)
@@ -349,6 +369,10 @@ int intel_pch_panel_fitting(struct intel_crtc_state *crtc_state,
 	if (ret)
 		return ret;
 
+	ret = intel_pch_pfit_check_cloning(crtc_state);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
-- 
2.23.0