[PATCH v3 6/7] drm: Validate encoder->possible_crtcs

[Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>]

From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

WARN if the encoder possible_crtcs is effectively empty or contains
bits for non-existing crtcs.

v2: Move to drm_mode_config_validate() (Daniel)
    Make the docs say we WARN when this is wrong (Daniel)
    Extract full_crtc_mask()

Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_mode_config.c | 27 ++++++++++++++++++++++++++-
 include/drm/drm_encoder.h         |  2 +-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index afc91447293a..4c1b350ddb95 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -581,6 +581,29 @@ static void validate_encoder_possible_clones(struct drm_encoder *encoder)
 	     encoder->possible_clones, encoder_mask);
 }
 
+static u32 full_crtc_mask(struct drm_device *dev)
+{
+	struct drm_crtc *crtc;
+	u32 crtc_mask = 0;
+
+	drm_for_each_crtc(crtc, dev)
+		crtc_mask |= drm_crtc_mask(crtc);
+
+	return crtc_mask;
+}
+
+static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
+{
+	u32 crtc_mask = full_crtc_mask(encoder->dev);
+
+	WARN((encoder->possible_crtcs & crtc_mask) == 0 ||
+	     (encoder->possible_crtcs & ~crtc_mask) != 0,
+	     "Bogus possible_crtcs: "
+	     "[ENCODER:%d:%s] possible_crtcs=0x%x (full crtc mask=0x%x)\n",
+	     encoder->base.id, encoder->name,
+	     encoder->possible_crtcs, crtc_mask);
+}
+
 void drm_mode_config_validate(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;
@@ -588,6 +611,8 @@ void drm_mode_config_validate(struct drm_device *dev)
 	drm_for_each_encoder(encoder, dev)
 		fixup_encoder_possible_clones(encoder);
 
-	drm_for_each_encoder(encoder, dev)
+	drm_for_each_encoder(encoder, dev) {
 		validate_encoder_possible_clones(encoder);
+		validate_encoder_possible_crtcs(encoder);
+	}
 }
diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
index 3741963b9587..b236269f41ac 100644
--- a/include/drm/drm_encoder.h
+++ b/include/drm/drm_encoder.h
@@ -142,7 +142,7 @@ struct drm_encoder {
 	 * the bits for all &drm_crtc objects this encoder can be connected to
 	 * before calling drm_dev_register().
 	 *
-	 * In reality almost every driver gets this wrong.
+	 * You will get a WARN if you get this wrong in the driver.
 	 *
 	 * Note that since CRTC objects can't be hotplugged the assigned indices
 	 * are stable and hence known before registering all objects.
-- 
2.24.1

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