disp: msm: perform delayed buf attach during secure transitions

While transitioning from secure usecases, the secure
context bank is attached back only during the commit
phase. This leads to invalid secure context-bank device
issue, when the prime_to_fd call is made for the next
frame. Avoid it, by attaching to default drm device
during the prime_to_fd call and reattach it to the
secure context-bank device at the delayed import time.

Change-Id: I43e6da7f117f20746943a48b5f2657e9ae2947ea
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>

msm/msm_gem.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
  * Copyright (C) 2013 Red Hat
  * Author: Rob Clark <robdclark@gmail.com>
  *
@@ -416,9 +416,36 @@ static int msm_gem_get_iova_locked(struct drm_gem_object *obj,
 
 	if (!vma) {
 		struct page **pages;
+		struct device *dev;
+		struct dma_buf *dmabuf;
+		bool reattach = false;
+
+		dev = msm_gem_get_aspace_device(aspace);
+		if (dev && obj->import_attach &&
+				(dev != obj->import_attach->dev)) {
+			dmabuf = obj->import_attach->dmabuf;
+
+			DRM_DEBUG("detach nsec-dev:%pK attach sec-dev:%pK\n",
+					obj->import_attach->dev, dev);
+			SDE_EVT32(obj->import_attach->dev, dev, msm_obj->sgt);
+
+			if (msm_obj->sgt)
+				dma_buf_unmap_attachment(obj->import_attach,
+					msm_obj->sgt, DMA_BIDIRECTIONAL);
+			dma_buf_detach(dmabuf, obj->import_attach);
+
+			obj->import_attach = dma_buf_attach(dmabuf, dev);
+			if (IS_ERR(obj->import_attach)) {
+				DRM_ERROR("dma_buf_attach failure, err=%ld\n",
+						PTR_ERR(obj->import_attach));
+				goto unlock;
+			}
+			reattach = true;
+		}
 
 		/* perform delayed import for buffers without existing sgt */
-		if (((msm_obj->flags & MSM_BO_EXTBUF) && !(msm_obj->sgt))) {
+		if (((msm_obj->flags & MSM_BO_EXTBUF) && !(msm_obj->sgt))
+				|| reattach) {
 			ret = msm_gem_delayed_import(obj);
 			if (ret) {
 				DRM_ERROR("delayed dma-buf import failed %d\n",