[PATCH v6 02/10] drm/hdcp: Avoid changing crtc state in hdcp atomic check

[Mark Yacoub <markyacoub@chromium.org>]

From: Sean Paul <seanpaul@chromium.org>

Instead of forcing a modeset in the hdcp atomic check, simply return
true if the content protection value is changing and let the driver
decide whether a modeset is required or not.

Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Mark Yacoub <markyacoub@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210913175747.47456-3-sean@poorly.run #v1
Link: https://patchwork.freedesktop.org/patch/msgid/20210915203834.1439-3-sean@poorly.run #v2
Link: https://patchwork.freedesktop.org/patch/msgid/20211001151145.55916-3-sean@poorly.run #v3
Link: https://patchwork.freedesktop.org/patch/msgid/20211105030434.2828845-3-sean@poorly.run #v4
Link: https://patchwork.freedesktop.org/patch/msgid/20220411204741.1074308-3-sean@poorly.run #v5

Changes in v2:
-None
Changes in v3:
-None
Changes in v4:
-None
Changes in v5:
-None
Changes in V6:
-Rebase: modifications in drm_hdcp_helper.c instead of drm_hdcp.c

---
 drivers/gpu/drm/display/drm_hdcp_helper.c   | 33 +++++++++++++++------
 drivers/gpu/drm/i915/display/intel_atomic.c |  6 ++--
 include/drm/display/drm_hdcp_helper.h       |  2 +-
 3 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdcp_helper.c b/drivers/gpu/drm/display/drm_hdcp_helper.c
index 7d910523b05f..a3896b0904b5 100644
--- a/drivers/gpu/drm/display/drm_hdcp_helper.c
+++ b/drivers/gpu/drm/display/drm_hdcp_helper.c
@@ -428,11 +428,14 @@ EXPORT_SYMBOL(drm_hdcp_update_content_protection);
  * @connector: drm_connector on which content protection state needs an update
  *
  * This function can be used by display drivers to perform an atomic check on the
- * hdcp state elements. If hdcp state has changed, this function will set
- * mode_changed on the crtc driving the connector so it can update its hardware
- * to match the hdcp state.
+ * hdcp state elements. If hdcp state has changed in a manner which requires the
+ * driver to enable or disable content protection, this function will return
+ * true.
+ *
+ * Returns:
+ * true if the driver must enable/disable hdcp, false otherwise
  */
-void drm_hdcp_atomic_check(struct drm_connector *connector,
+bool drm_hdcp_atomic_check(struct drm_connector *connector,
 			   struct drm_atomic_state *state)
 {
 	struct drm_connector_state *new_conn_state, *old_conn_state;
@@ -450,10 +453,12 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
 		 * If the connector is being disabled with CP enabled, mark it
 		 * desired so it's re-enabled when the connector is brought back
 		 */
-		if (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED)
+		if (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED) {
 			new_conn_state->content_protection =
 				DRM_MODE_CONTENT_PROTECTION_DESIRED;
-		return;
+			return true;
+		}
+		return false;
 	}
 
 	new_crtc_state =
@@ -465,9 +470,19 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
 	*/
 	if (drm_atomic_crtc_needs_modeset(new_crtc_state) &&
 	    (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED &&
-	     new_hdcp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED))
+	     new_hdcp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED)) {
 		new_conn_state->content_protection =
 			DRM_MODE_CONTENT_PROTECTION_DESIRED;
+		return true;
+	}
+
+	/*
+	 * Coming back from disable or changing CRTC with DESIRED state requires
+	 * that the driver try CP enable.
+	 */
+	if (new_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
+	    new_conn_state->crtc != old_conn_state->crtc)
+		return true;
 
 	/*
 	 * Nothing to do if content type is unchanged and one of:
@@ -482,9 +497,9 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
 	     new_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED)) {
 		if (old_conn_state->hdcp_content_type ==
 		    new_conn_state->hdcp_content_type)
-			return;
+			return false;
 	}
 
-	new_crtc_state->mode_changed = true;
+	return true;
 }
 EXPORT_SYMBOL(drm_hdcp_atomic_check);
diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
index 8a473199c4bf..a2067cbae2d5 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic.c
@@ -123,8 +123,6 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
 		to_intel_digital_connector_state(old_state);
 	struct drm_crtc_state *crtc_state;
 
-	drm_hdcp_atomic_check(conn, state);
-
 	if (!new_state->crtc)
 		return 0;
 
@@ -140,8 +138,8 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
 	    new_conn_state->base.picture_aspect_ratio != old_conn_state->base.picture_aspect_ratio ||
 	    new_conn_state->base.content_type != old_conn_state->base.content_type ||
 	    new_conn_state->base.scaling_mode != old_conn_state->base.scaling_mode ||
-	    new_conn_state->base.privacy_screen_sw_state != old_conn_state->base.privacy_screen_sw_state ||
-	    !drm_connector_atomic_hdr_metadata_equal(old_state, new_state))
+	    !drm_connector_atomic_hdr_metadata_equal(old_state, new_state) ||
+	    drm_hdcp_atomic_check(conn, state))
 		crtc_state->mode_changed = true;
 
 	return 0;
diff --git a/include/drm/display/drm_hdcp_helper.h b/include/drm/display/drm_hdcp_helper.h
index dd02b2e72a50..cb2cc5002f65 100644
--- a/include/drm/display/drm_hdcp_helper.h
+++ b/include/drm/display/drm_hdcp_helper.h
@@ -19,7 +19,7 @@ int drm_hdcp_check_ksvs_revoked(struct drm_device *dev, u8 *ksvs, u32 ksv_count)
 int drm_connector_attach_content_protection_property(struct drm_connector *connector,
 						     bool hdcp_content_type);
 void drm_hdcp_update_content_protection(struct drm_connector *connector, u64 val);
-void drm_hdcp_atomic_check(struct drm_connector *connector,
+bool drm_hdcp_atomic_check(struct drm_connector *connector,
 			   struct drm_atomic_state *state);
 
 #endif
-- 
2.39.0.246.g2a6d74b583-goog