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From:   Mark Yacoub <markyacoub@chromium.org>
To:     David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc:     seanpaul@chromium.org, suraj.kandpal@intel.com,
        dianders@chromium.org, Jani Nikula <jani.nikula@intel.com>,
        Mark Yacoub <markyacoub@chromium.org>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        intel-gfx@lists.freedesktop.org
Subject: [PATCH v7 02/10] drm/hdcp: Avoid changing crtc state in hdcp atomic check
Date:   Fri, 24 Mar 2023 15:20:49 -0400
Message-Id: <20230324192058.3916571-3-markyacoub@google.com>
In-Reply-To: <20230324192058.3916571-1-markyacoub@google.com>
References: <20230324192058.3916571-1-markyacoub@google.com>
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From: Sean Paul <seanpaul@chromium.org>

Instead of forcing a modeset in the hdcp atomic check, rename to
drm_hdcp_has_changed and 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>

---
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
Changes in v7:
-Renamed the function from drm_hdcp_atomic_check to drm_hdcp_has_changed
(Dmitry Baryshkov)

 drivers/gpu/drm/display/drm_hdcp_helper.c   | 39 ++++++++++++++-------
 drivers/gpu/drm/i915/display/intel_atomic.c |  6 ++--
 include/drm/display/drm_hdcp_helper.h       |  2 +-
 3 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_hdcp_helper.c b/drivers/gpu/drm/display/drm_hdcp_helper.c
index 7ca390b3ea106..34baf2b97cd87 100644
--- a/drivers/gpu/drm/display/drm_hdcp_helper.c
+++ b/drivers/gpu/drm/display/drm_hdcp_helper.c
@@ -422,18 +422,21 @@ void drm_hdcp_update_content_protection(struct drm_connector *connector,
 EXPORT_SYMBOL(drm_hdcp_update_content_protection);
 
 /**
- * drm_hdcp_atomic_check - Helper for drivers to call during connector->atomic_check
+ * drm_hdcp_has_changed - Helper for drivers to call during connector->atomic_check
  *
  * @state: pointer to the atomic state being checked
  * @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,
-			   struct drm_atomic_state *state)
+bool drm_hdcp_has_changed(struct drm_connector *connector,
+			  struct drm_atomic_state *state)
 {
 	struct drm_connector_state *new_conn_state, *old_conn_state;
 	struct drm_crtc_state *new_crtc_state;
@@ -450,19 +453,31 @@ 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 =
 		drm_atomic_get_new_crtc_state(state, new_conn_state->crtc);
 	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 UNDESIRED state, CRTC change or re-enablement requires
+	 * the driver to 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:
@@ -477,9 +492,9 @@ 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);
+EXPORT_SYMBOL(drm_hdcp_has_changed);
diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
index 934ca9dcecc54..bce4aba752974 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_has_changed(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 dd02b2e72a502..703421fcdf96c 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_has_changed(struct drm_connector *connector,
 			   struct drm_atomic_state *state);
 
 #endif
-- 
2.40.0.348.gf938b09366-goog