[PATCH hwc v2 06/18] drm_hwcomposer: Add writeback connector support

[Alexandru Gheorghe]

Writeback connector is a special case of connector, which can be
linked to a CRTC in order to get the result of the composition back to
a memory buffer. This had not been merged to the mainline kernel yet,
latest version of the kernel patches could be found here [1].

[1] https://lists.freedesktop.org/archives/dri-devel/2018-February/167703.html

Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe at arm.com>
---
 drmconnector.cpp | 42 +++++++++++++++++++++++++++++++++++++++++-
 drmconnector.h   |  7 +++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drmconnector.cpp b/drmconnector.cpp
index 145518f..e482832 100644
--- a/drmconnector.cpp
+++ b/drmconnector.cpp
@@ -52,6 +52,26 @@ int DrmConnector::Init() {
     ALOGE("Could not get CRTC_ID property\n");
     return ret;
   }
+  if (writeback()) {
+    ret = drm_->GetConnectorProperty(*this, "WRITEBACK_PIXEL_FORMATS",
+                                     &writeback_pixel_formats_);
+    if (ret) {
+      ALOGE("Could not get WRITEBACK_PIXEL_FORMATS connector_id = %d\n", id_);
+      return ret;
+    }
+    ret =
+        drm_->GetConnectorProperty(*this, "WRITEBACK_FB_ID", &writeback_fb_id_);
+    if (ret) {
+      ALOGE("Could not get WRITEBACK_FB_ID connector_id = %d\n", id_);
+      return ret;
+    }
+    ret = drm_->GetConnectorProperty(*this, "WRITEBACK_OUT_FENCE_PTR",
+                                     &writeback_out_fence_);
+    if (ret) {
+      ALOGE("Could not get WRITEBACK_OUT_FENCE_PTR connector_id = %d\n", id_);
+      return ret;
+    }
+  }
   return 0;
 }
 
@@ -78,8 +98,16 @@ bool DrmConnector::external() const {
          type_ == DRM_MODE_CONNECTOR_VGA;
 }
 
+bool DrmConnector::writeback() const {
+#ifdef DRM_MODE_CONNECTOR_WRITEBACK
+  return type_ == DRM_MODE_CONNECTOR_WRITEBACK;
+#else
+  return false;
+#endif
+}
+
 bool DrmConnector::valid_type() const {
-  return internal() || external();
+  return internal() || external() || writeback();
 }
 
 int DrmConnector::UpdateModes() {
@@ -130,6 +158,18 @@ const DrmProperty &DrmConnector::crtc_id_property() const {
   return crtc_id_property_;
 }
 
+const DrmProperty &DrmConnector::writeback_pixel_formats() const {
+  return writeback_pixel_formats_;
+}
+
+const DrmProperty &DrmConnector::writeback_fb_id() const {
+  return writeback_fb_id_;
+}
+
+const DrmProperty &DrmConnector::writeback_out_fence() const {
+  return writeback_out_fence_;
+}
+
 DrmEncoder *DrmConnector::encoder() const {
   return encoder_;
 }
diff --git a/drmconnector.h b/drmconnector.h
index 5601e06..e139730 100644
--- a/drmconnector.h
+++ b/drmconnector.h
@@ -46,6 +46,7 @@ class DrmConnector {
 
   bool internal() const;
   bool external() const;
+  bool writeback() const;
   bool valid_type() const;
 
   int UpdateModes();
@@ -58,6 +59,9 @@ class DrmConnector {
 
   const DrmProperty &dpms_property() const;
   const DrmProperty &crtc_id_property() const;
+  const DrmProperty &writeback_pixel_formats() const;
+  const DrmProperty &writeback_fb_id() const;
+  const DrmProperty &writeback_out_fence() const;
 
   const std::vector<DrmEncoder *> &possible_encoders() const {
     return possible_encoders_;
@@ -88,6 +92,9 @@ class DrmConnector {
 
   DrmProperty dpms_property_;
   DrmProperty crtc_id_property_;
+  DrmProperty writeback_pixel_formats_;
+  DrmProperty writeback_fb_id_;
+  DrmProperty writeback_out_fence_;
 
   std::vector<DrmEncoder *> possible_encoders_;
 };
-- 
2.7.4