commit 613a9440a035f71a1e5d3da50b3576ce48c62d8e
author Drew Davenport <ddavenport@google.com> Wed Dec 04 09:46:06 2024 -0700
committer Drew Davenport <ddavenport@google.com> Wed Dec 04 09:54:14 2024 -0700
tree d1a38d5fca0d592c9dcf20ad684ec6e6b42e9e61
parent 2852f7d46de5d0109a828a13589f1eb518f1acd6

drm_hwcomposer: Add property for config groups

Android framework will change between configs in the same config group
dynamically, to support the Multiple refresh rate [1] feature. If the
display driver does not support changing modes seamlessly, there will be
visible artifacts (blank screen) when changing refresh rates.

Add a property to disable config grouping on devices that do not support
seamless mode changes. Set the default value to enable config grouping.

[1] https://source.android.com/docs/core/graphics/multiple-refresh-rate

Change-Id: Iec5927ea3af063669f6f7b7aa430e541c1c35428
Signed-off-by: Drew Davenport <ddavenport@google.com>

hwc2_device/HwcDisplayConfigs.cpp

diff --git a/hwc2_device/HwcDisplayConfigs.cpp b/hwc2_device/HwcDisplayConfigs.cpp
index 3645356..fa1d2a9 100644
--- a/hwc2_device/HwcDisplayConfigs.cpp
+++ b/hwc2_device/HwcDisplayConfigs.cpp
@@ -23,6 +23,7 @@
 
 #include "drm/DrmConnector.h"
 #include "utils/log.h"
+#include "utils/properties.h"
 
 constexpr uint32_t kHeadlessModeDisplayWidthMm = 163;
 constexpr uint32_t kHeadlessModeDisplayHeightMm = 122;
@@ -113,17 +114,20 @@
 
   auto first_config_id = last_config_id;
   uint32_t last_group_id = 1;
+  const bool use_config_groups = Properties::UseConfigGroups();
 
   /* Group modes */
   for (const auto &mode : connector.GetModes()) {
     /* Find group for the new mode or create new group */
     uint32_t group_found = 0;
-    for (auto &hwc_config : hwc_configs) {
-      if (mode.GetRawMode().hdisplay ==
-              hwc_config.second.mode.GetRawMode().hdisplay &&
-          mode.GetRawMode().vdisplay ==
-              hwc_config.second.mode.GetRawMode().vdisplay) {
-        group_found = hwc_config.second.group_id;
+    if (use_config_groups) {
+      for (auto &hwc_config : hwc_configs) {
+        if (mode.GetRawMode().hdisplay ==
+                hwc_config.second.mode.GetRawMode().hdisplay &&
+            mode.GetRawMode().vdisplay ==
+                hwc_config.second.mode.GetRawMode().vdisplay) {
+          group_found = hwc_config.second.group_id;
+        }
       }
     }
     if (group_found == 0) {

utils/properties.cpp

diff --git a/utils/properties.cpp b/utils/properties.cpp
index 4547e74..a855c94 100644
--- a/utils/properties.cpp
+++ b/utils/properties.cpp
@@ -25,3 +25,7 @@
   return (property_get_bool("ro.vendor.hwc.drm.present_fence_not_reliable",
                             0) != 0);
 }
+
+auto Properties::UseConfigGroups() -> bool {
+  return (property_get_bool("ro.vendor.hwc.drm.use_config_groups", 1) != 0);
+}

utils/properties.h

diff --git a/utils/properties.h b/utils/properties.h
index f5816cb..15c2fb2 100644
--- a/utils/properties.h
+++ b/utils/properties.h
@@ -77,4 +77,5 @@
 class Properties {
  public:
   static auto IsPresentFenceNotReliable() -> bool;
+  static auto UseConfigGroups() -> bool;
 };