SF: parsing Detailed Timing Descriptor in the framework
The first DTD in an edid is the preferred timing which allows to get
a more precise and more often correct physical size for a display. This
can be used to estimate or correct the dpi in case the edid reports the
wrong size and hwc is not providing the right value.
See edid spec: https://glenwing.github.io/docs/VESA-EEDID-A2.pdf
Flag: com.android.graphics.surfaceflinger.flags.correct_dpi_with_display_size
Bug: 361413340
Test: DisplayIdentification_test
Test: HWComposerTest
Test: manual - see bug and doc
Change-Id: I0bb85dcf8039f923f1ac892c4a1d6bda771dbf4f
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index c83e0da..bd093f5 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -76,6 +76,7 @@
using aidl::android::hardware::graphics::common::HdrConversionStrategy;
using aidl::android::hardware::graphics::composer3::Capability;
using aidl::android::hardware::graphics::composer3::DisplayCapability;
+using aidl::android::hardware::graphics::composer3::DisplayConfiguration;
using namespace std::string_literals;
namespace android {
@@ -222,8 +223,8 @@
return true;
}
-void HWComposer::allocatePhysicalDisplay(hal::HWDisplayId hwcDisplayId,
- PhysicalDisplayId displayId) {
+void HWComposer::allocatePhysicalDisplay(hal::HWDisplayId hwcDisplayId, PhysicalDisplayId displayId,
+ std::optional<ui::Size> physicalSize) {
mPhysicalDisplayIdMap[hwcDisplayId] = displayId;
if (!mPrimaryHwcDisplayId) {
@@ -235,6 +236,7 @@
std::make_unique<HWC2::impl::Display>(*mComposer.get(), mCapabilities, hwcDisplayId,
hal::DisplayType::PHYSICAL);
newDisplay->setConnected(true);
+ newDisplay->setPhysicalSizeInMm(physicalSize);
displayData.hwcDisplay = std::move(newDisplay);
}
@@ -276,6 +278,47 @@
return getModesFromLegacyDisplayConfigs(hwcDisplayId);
}
+DisplayConfiguration::Dpi HWComposer::getEstimatedDotsPerInchFromSize(
+ uint64_t hwcDisplayId, const HWCDisplayMode& hwcMode) const {
+ if (!FlagManager::getInstance().correct_dpi_with_display_size()) {
+ return {-1, -1};
+ }
+ if (const auto displayId = toPhysicalDisplayId(hwcDisplayId)) {
+ if (const auto it = mDisplayData.find(displayId.value());
+ it != mDisplayData.end() && it->second.hwcDisplay->getPhysicalSizeInMm()) {
+ ui::Size size = it->second.hwcDisplay->getPhysicalSizeInMm().value();
+ if (hwcMode.width > 0 && hwcMode.height > 0 && size.width > 0 && size.height > 0) {
+ static constexpr float kMmPerInch = 25.4f;
+ return {hwcMode.width * kMmPerInch / size.width,
+ hwcMode.height * kMmPerInch / size.height};
+ }
+ }
+ }
+ return {-1, -1};
+}
+
+DisplayConfiguration::Dpi HWComposer::correctedDpiIfneeded(
+ DisplayConfiguration::Dpi dpi, DisplayConfiguration::Dpi estimatedDpi) const {
+ // hwc can be unreliable when it comes to dpi. A rough estimated dpi may yield better
+ // results. For instance, libdrm and bad edid may result in a dpi of {350, 290} for a
+ // 16:9 3840x2160 display, which would match a 4:3 aspect ratio.
+ // The logic here checks if hwc was able to provide some dpi, and if so if the dpi
+ // disparity between the axes is more reasonable than a rough estimate, otherwise use
+ // the estimated dpi as a corrected value.
+ if (estimatedDpi.x == -1 || estimatedDpi.x == -1) {
+ return dpi;
+ }
+ if (dpi.x == -1 || dpi.y == -1) {
+ return estimatedDpi;
+ }
+ if (std::min(dpi.x, dpi.y) != 0 && std::min(estimatedDpi.x, estimatedDpi.y) != 0 &&
+ abs(dpi.x - dpi.y) / std::min(dpi.x, dpi.y) >
+ abs(estimatedDpi.x - estimatedDpi.y) / std::min(estimatedDpi.x, estimatedDpi.y)) {
+ return estimatedDpi;
+ }
+ return dpi;
+}
+
std::vector<HWComposer::HWCDisplayMode> HWComposer::getModesFromDisplayConfigurations(
uint64_t hwcDisplayId, int32_t maxFrameIntervalNs) const {
std::vector<hal::DisplayConfiguration> configs;
@@ -294,9 +337,16 @@
.configGroup = config.configGroup,
.vrrConfig = config.vrrConfig};
+ const DisplayConfiguration::Dpi estimatedDPI =
+ getEstimatedDotsPerInchFromSize(hwcDisplayId, hwcMode);
if (config.dpi) {
- hwcMode.dpiX = config.dpi->x;
- hwcMode.dpiY = config.dpi->y;
+ const DisplayConfiguration::Dpi dpi =
+ correctedDpiIfneeded(config.dpi.value(), estimatedDPI);
+ hwcMode.dpiX = dpi.x;
+ hwcMode.dpiY = dpi.y;
+ } else if (estimatedDPI.x != -1 && estimatedDPI.y != -1) {
+ hwcMode.dpiX = estimatedDPI.x;
+ hwcMode.dpiY = estimatedDPI.y;
}
if (!mEnableVrrTimeout) {
@@ -328,12 +378,14 @@
const int32_t dpiX = getAttribute(hwcDisplayId, configId, hal::Attribute::DPI_X);
const int32_t dpiY = getAttribute(hwcDisplayId, configId, hal::Attribute::DPI_Y);
- if (dpiX != -1) {
- hwcMode.dpiX = static_cast<float>(dpiX) / 1000.f;
- }
- if (dpiY != -1) {
- hwcMode.dpiY = static_cast<float>(dpiY) / 1000.f;
- }
+ const DisplayConfiguration::Dpi hwcDpi =
+ DisplayConfiguration::Dpi{dpiX == -1 ? dpiY : dpiX / 1000.f,
+ dpiY == -1 ? dpiY : dpiY / 1000.f};
+ const DisplayConfiguration::Dpi estimatedDPI =
+ getEstimatedDotsPerInchFromSize(hwcDisplayId, hwcMode);
+ const DisplayConfiguration::Dpi dpi = correctedDpiIfneeded(hwcDpi, estimatedDPI);
+ hwcMode.dpiX = dpi.x;
+ hwcMode.dpiY = dpi.y;
modes.push_back(hwcMode);
}
@@ -1072,6 +1124,8 @@
getDisplayIdentificationData(hwcDisplayId, &port, &data);
if (auto newInfo = parseDisplayIdentificationData(port, data)) {
info->deviceProductInfo = std::move(newInfo->deviceProductInfo);
+ info->preferredDetailedTimingDescriptor =
+ std::move(newInfo->preferredDetailedTimingDescriptor);
} else {
ALOGE("Failed to parse identification data for display %" PRIu64, hwcDisplayId);
}
@@ -1114,7 +1168,11 @@
}
if (!isConnected(info->id)) {
- allocatePhysicalDisplay(hwcDisplayId, info->id);
+ std::optional<ui::Size> size = std::nullopt;
+ if (info->preferredDetailedTimingDescriptor) {
+ size = info->preferredDetailedTimingDescriptor->physicalSizeInMm;
+ }
+ allocatePhysicalDisplay(hwcDisplayId, info->id, size);
}
return info;
}