drm/i915: consolidate and tighten encoder cloning checks

Only lvds/tv did actually check for cloning or not, but many more
places should.

Notices because my ivb tried to enable both cpu edp and vga on the
first crtc - the resulting confusion between has_pch_encoder,
has_dp_encoder but not actually being a pch dp encoder resulting in
hilarity (hitting a BUG).

We _really_ need an igt to random-walk our modeset space more
exhaustively.

The bug seems to have been exposed due to a race in the hw load
detection support for VGA: Right after a hotplug VGA was still
detected as connected, but obviously reading the EDID wasn't possible
any more. Hence why restarting X a bit later fixed things. Due to the
1024x756 fallback resolution suddenly more outputs had the same
resolution.

On top of that SNA was confused with the possible_clones mask, trying
to clone outputs which cannot be cloned. That bug is now fixed with

commit fc1e0702b25e647cb423851fb7228989fec28bd6
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed May 29 11:25:28 2013 +0100

    sna: fixup up possible_clones kms->X impedance mismatch

v2: Kill intel_encoder_check_is_cloned, spotted by Paulo.

v3: Drop the now unused pipe param.

v4: Kill the stray printk Chris spotted.

v5: Elaborate on how the bug in userspace happened and why it was racy
to reproduce.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -5868,27 +5868,9 @@ static int haswell_crtc_mode_set(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
-	int pipe = intel_crtc->pipe;
 	int plane = intel_crtc->plane;
-	int num_connectors = 0;
-	bool is_cpu_edp = false;
-	struct intel_encoder *encoder;
 	int ret;
 
-	for_each_encoder_on_crtc(dev, crtc, encoder) {
-		switch (encoder->type) {
-		case INTEL_OUTPUT_EDP:
-			if (enc_to_dig_port(&encoder->base)->port == PORT_A)
-				is_cpu_edp = true;
-			break;
-		}
-
-		num_connectors++;
-	}
-
-	WARN(num_connectors != 1, "%d connectors attached to pipe %c\n",
-	     num_connectors, pipe_name(pipe));
-
 	if (!intel_ddi_pll_mode_set(crtc))
 		return -EINVAL;
 
@@ -7564,28 +7546,6 @@ static struct drm_crtc_helper_funcs intel_helper_funcs = {
 	.load_lut = intel_crtc_load_lut,
 };
 
-bool intel_encoder_check_is_cloned(struct intel_encoder *encoder)
-{
-	struct intel_encoder *other_encoder;
-	struct drm_crtc *crtc = &encoder->new_crtc->base;
-
-	if (WARN_ON(!crtc))
-		return false;
-
-	list_for_each_entry(other_encoder,
-			    &crtc->dev->mode_config.encoder_list,
-			    base.head) {
-
-		if (&other_encoder->new_crtc->base != crtc ||
-		    encoder == other_encoder)
-			continue;
-		else
-			return true;
-	}
-
-	return false;
-}
-
 static bool intel_encoder_crtc_ok(struct drm_encoder *encoder,
 				  struct drm_crtc *crtc)
 {
@@ -7769,6 +7729,25 @@ static void intel_dump_pipe_config(struct intel_crtc *crtc,
 	DRM_DEBUG_KMS("ips: %i\n", pipe_config->ips_enabled);
 }
 
+static bool check_encoder_cloning(struct drm_crtc *crtc)
+{
+	int num_encoders = 0;
+	bool uncloneable_encoders = false;
+	struct intel_encoder *encoder;
+
+	list_for_each_entry(encoder, &crtc->dev->mode_config.encoder_list,
+			    base.head) {
+		if (&encoder->new_crtc->base != crtc)
+			continue;
+
+		num_encoders++;
+		if (!encoder->cloneable)
+			uncloneable_encoders = true;
+	}
+
+	return !(num_encoders > 1 && uncloneable_encoders);
+}
+
 static struct intel_crtc_config *
 intel_modeset_pipe_config(struct drm_crtc *crtc,
 			  struct drm_framebuffer *fb,
@@ -7781,6 +7760,11 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
 	int plane_bpp, ret = -EINVAL;
 	bool retry = true;
 
+	if (!check_encoder_cloning(crtc)) {
+		DRM_DEBUG_KMS("rejecting invalid cloning configuration\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	pipe_config = kzalloc(sizeof(*pipe_config), GFP_KERNEL);
 	if (!pipe_config)
 		return ERR_PTR(-ENOMEM);

drivers/gpu/drm/i915/intel_drv.h

@@ -629,7 +629,6 @@ extern void intel_crtc_load_lut(struct drm_crtc *crtc);
 extern void intel_crtc_update_dpms(struct drm_crtc *crtc);
 extern void intel_encoder_destroy(struct drm_encoder *encoder);
 extern void intel_encoder_dpms(struct intel_encoder *encoder, int mode);
-extern bool intel_encoder_check_is_cloned(struct intel_encoder *encoder);
 extern void intel_connector_dpms(struct drm_connector *, int mode);
 extern bool intel_connector_get_hw_state(struct intel_connector *connector);
 extern void intel_modeset_check_state(struct drm_device *dev);

drivers/gpu/drm/i915/intel_lvds.c

@@ -264,9 +264,6 @@ static bool intel_lvds_compute_config(struct intel_encoder *intel_encoder,
 		return false;
 	}
 
-	if (intel_encoder_check_is_cloned(&lvds_encoder->base))
-		return false;
-
 	if ((I915_READ(lvds_encoder->reg) & LVDS_A3_POWER_MASK) ==
 	    LVDS_A3_POWER_UP)
 		lvds_bpp = 8*3;

drivers/gpu/drm/i915/intel_tv.c

@@ -914,9 +914,6 @@ intel_tv_compute_config(struct intel_encoder *encoder,
 	if (!tv_mode)
 		return false;
 
-	if (intel_encoder_check_is_cloned(&intel_tv->base))
-		return false;
-
 	pipe_config->adjusted_mode.clock = tv_mode->clock;
 	DRM_DEBUG_KMS("forcing bpc to 8 for TV\n");
 	pipe_config->pipe_bpp = 8*3;