power-profiles-daemon: preserve backward compatibility for driver

Keep the {driver} placeholder working and support older
power-profiles-daemon versions that only expose a single Driver DBus
property, while still reading the new CpuDriver/PlatformDriver fields.

- Read the legacy Driver property and fall back to it when CpuDriver or
  PlatformDriver are missing (older daemon).
- Derive {driver} from CpuDriver when the daemon no longer exposes
  Driver (recent daemon), so existing configs using {driver} keep
  working.
- Align the default tooltip-format in the constructor with the
  documented default.

include/modules/power_profiles_daemon.hpp

@@ -9,10 +9,18 @@ namespace waybar::modules {
 
 struct Profile {
   std::string name;
+  // Legacy driver field, kept for backward compatibility with the
+  // `{driver}` format placeholder and with older power-profiles-daemon
+  // versions that only expose a single `Driver` DBus property.
+  std::string driver;
   std::string cpuDriver;
   std::string platformDriver;
 
-  Profile(std::string n, std::string cd, std::string pd) : name(std::move(n)), cpuDriver(std::move(cd)), platformDriver(std::move(pd)) {}
+  Profile(std::string n, std::string d, std::string cd, std::string pd)
+      : name(std::move(n)),
+        driver(std::move(d)),
+        cpuDriver(std::move(cd)),
+        platformDriver(std::move(pd)) {}
 };
 
 class PowerProfilesDaemon : public ALabel {

man/waybar-power-profiles-daemon.5.scd

@@ -26,7 +26,7 @@ $XDG_CONFIG_HOME/waybar/config
 |[ *tooltip-format*
 :[ string
 :[ "Power profile: {profile}\\nCPU driver: {cpu_driver}\\nPlatform driver: {platform_driver}"
-:[ Messaged displayed in the module tooltip. {icon} and {profile} are respectively substituted with the icon representing the active profile and its full name.
+:[ Messaged displayed in the module tooltip. {icon} and {profile} are respectively substituted with the icon representing the active profile and its full name. {cpu_driver} and {platform_driver} are substituted with the CPU and platform drivers reported by recent power-profiles-daemon versions. {driver} is kept for backward compatibility: it resolves to the legacy single driver on older daemons and falls back to the CPU driver on recent ones.
 |[ *tooltip*
 :[ bool
 :[ true

src/modules/power_profiles_daemon.cpp

@@ -12,7 +12,8 @@ PowerProfilesDaemon::PowerProfilesDaemon(const std::string& id, const Json::Valu
   if (config_["tooltip-format"].isString()) {
     tooltipFormat_ = config_["tooltip-format"].asString();
   } else {
-    tooltipFormat_ = "Power profile: {profile}\nCpuDriver: {cpu_driver}";
+    tooltipFormat_ =
+        "Power profile: {profile}\nCPU driver: {cpu_driver}\nPlatform driver: {platform_driver}";
   }
   // Fasten your seatbelt, we're up for quite a ride. The rest of the
   // init is performed asynchronously. There's 2 callbacks involved.
@@ -95,11 +96,17 @@ void PowerProfilesDaemon::populateInitState() {
   powerProfilesProxy_->get_cached_property(profilesVariant, "Profiles");
   for (auto& variantDict : profilesVariant.get()) {
     Glib::ustring name;
+    // Legacy single `Driver` property, still exposed by older
+    // power-profiles-daemon versions.
+    Glib::ustring driver;
     Glib::ustring cpuDriver;
     Glib::ustring platformDriver;
     if (auto p = variantDict.find("Profile"); p != variantDict.end()) {
       name = p->second.get();
     }
+    if (auto d = variantDict.find("Driver"); d != variantDict.end()) {
+      driver = d->second.get();
+    }
     if (auto cd = variantDict.find("CpuDriver"); cd != variantDict.end()) {
       cpuDriver = cd->second.get();
     }
@@ -107,17 +114,33 @@ void PowerProfilesDaemon::populateInitState() {
       platformDriver = pd->second.get();
     }
 
+    // Recent power-profiles-daemon versions split the single `Driver`
+    // property into `CpuDriver` and `PlatformDriver`. When talking to an
+    // older daemon that only exposes `Driver`, fall back to it so the new
+    // {cpu_driver}/{platform_driver} placeholders still resolve.
     if (cpuDriver.empty()) {
-      cpuDriver = "Unavailable";
-      spdlog::warn("Cannot find power profiles daemon cpu driver.");
+      cpuDriver = driver;
     }
     if (platformDriver.empty()) {
+      platformDriver = driver;
+    }
+    // Conversely, keep the legacy {driver} placeholder working against a
+    // recent daemon that no longer exposes `Driver` by deriving it from
+    // the CPU driver.
+    if (driver.empty()) {
+      driver = cpuDriver;
+    }
+
+    if (driver.empty()) {
+      driver = "Unavailable";
+      cpuDriver = "Unavailable";
       platformDriver = "Unavailable";
-      spdlog::warn("Cannot find power profiles daemon platform driver.");
+      spdlog::warn("Cannot find power profiles daemon driver.");
     }
 
     if (!name.empty()) {
-      availableProfiles_.emplace_back(std::move(name), std::move(cpuDriver), std::move(platformDriver));
+      availableProfiles_.emplace_back(std::move(name), std::move(driver), std::move(cpuDriver),
+                                      std::move(platformDriver));
     } else {
       spdlog::error(
           "Power profiles daemon: power-profiles-daemon sent us an empty power profile name. "
@@ -167,6 +190,8 @@ auto PowerProfilesDaemon::update() -> void {
     // Set label
     fmt::dynamic_format_arg_store<fmt::format_context> store;
     store.push_back(fmt::arg("profile", profile.name));
+    // Legacy placeholder, kept for backward compatibility with existing configs.
+    store.push_back(fmt::arg("driver", profile.driver));
     store.push_back(fmt::arg("cpu_driver", profile.cpuDriver));
     store.push_back(fmt::arg("platform_driver", profile.platformDriver));
     store.push_back(fmt::arg("icon", getIcon(0, profile.name)));