drm/i915/pxp: add device link between i915 and mei_pxp

Add device link with i915 as consumer and mei_pxp as supplier
to ensure proper ordering of power flows.

V2: condition on absence of heci_pxp to filter out DG
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230125082637.118970-3-alan.previn.teres.alexis@intel.com

drivers/gpu/drm/i915/pxp/intel_pxp_tee.c

@@ -127,6 +127,12 @@ static int i915_pxp_tee_component_bind(struct device *i915_kdev,
 	intel_wakeref_t wakeref;
 	int ret = 0;
 
+	if (!HAS_HECI_PXP(i915)) {
+		pxp->dev_link = device_link_add(i915_kdev, tee_kdev, DL_FLAG_STATELESS);
+		if (drm_WARN_ON(&i915->drm, !pxp->dev_link))
+			return -ENODEV;
+	}
+
 	mutex_lock(&pxp->tee_mutex);
 	pxp->pxp_component = data;
 	pxp->pxp_component->tee_dev = tee_kdev;
@@ -169,6 +175,11 @@ static void i915_pxp_tee_component_unbind(struct device *i915_kdev,
 	mutex_lock(&pxp->tee_mutex);
 	pxp->pxp_component = NULL;
 	mutex_unlock(&pxp->tee_mutex);
+
+	if (pxp->dev_link) {
+		device_link_del(pxp->dev_link);
+		pxp->dev_link = NULL;
+	}
 }
 
 static const struct component_ops i915_pxp_tee_component_ops = {

drivers/gpu/drm/i915/pxp/intel_pxp_types.h

@@ -32,6 +32,9 @@ struct intel_pxp {
 	 * which are protected by &tee_mutex.
 	 */
 	struct i915_pxp_component *pxp_component;
+
+	/* @dev_link: Enforce module relationship for power management ordering. */
+	struct device_link *dev_link;
 	/**
 	 * @pxp_component_added: track if the pxp component has been added.
 	 * Set and cleared in tee init and fini functions respectively.