fix(HDMI): Prevent HDMI CEC from powering on display at boot

src/boot/FPPINIT.cpp

@@ -241,7 +241,7 @@ int main(int argc, char* argv[]) {
             // dup2 replaces that fd before we print anything, so this capture
             // still works even though the parent shell redirected us away.
             teeOutput(logFile, "fppinit", "Audio", getpid());
-        } else if (action == "configureBBB" || action == "applyThermal" || action == "resetThermal" || action == "installKiosk" || action == "setupPiRTC") {
+        } else if (action == "configureBBB" || action == "applyThermal" || action == "resetThermal" || action == "installKiosk" || action == "setupPiRTC" || action == "setupHDMICEC") {
             // Same gap as setupNetwork: invoked directly via PHP exec(), output
             // otherwise lives only in that request's $output/HTTP response.
             teeOutput(logFile, "fppinit", "Config", getpid());
@@ -283,6 +283,7 @@ int main(int argc, char* argv[]) {
         // After DetectCape() above, so a cape shipping DisablePiRTC in its
         // defaultSettings is honoured on the boot it is first detected on.
         setupPiRTCConfig();
+        setupHDMICECConfig();
         int reboot = getRawSettingInt("rebootFlag", 0);
         if (reboot && !needReboot) {
             printf("FPP - Clearing reboot flags\n");
@@ -475,6 +476,9 @@ int main(int argc, char* argv[]) {
     } else if (action == "setupPiRTC") {
         // The UI's "reboot": 1 on DisablePiRTC prompts the user; don't reboot here.
         setupPiRTCConfig(false);
+    } else if (action == "setupHDMICEC") {
+        // The UI's "reboot": 1 on DisableHDMICECInit prompts the user; don't reboot here.
+        setupHDMICECConfig(false);
     } else if (action == "setupNetwork") {
         PutFileContents(networkSetupMut, "1");
         setupNetwork(true);

src/boot/FPPINIT.h

@@ -94,6 +94,7 @@ void startZRAMSwap();
 void startDiskSwap();
 void setupChannelOutputs();
 void setupPiRTCConfig(bool rebootIfChanged = true);
+void setupHDMICECConfig(bool rebootIfChanged = true);
 void handleRebootActions();
 
 // ---------------------------------------------------------------------------

src/boot/FPPINIT_Config.cpp

@@ -1257,6 +1257,83 @@ void setupPiRTCConfig(bool rebootIfChanged) {
 #endif
 }
 
+#ifdef PLATFORM_PI
+// Suppress the initial CEC Active Source at boot that wakes projectors/TVs
+// (e.g. Epson L210SF, issue #2938). When enabled, adds hdmi_ignore_cec_init=1
+// to config.txt. Unlike hdmi_ignore_cec=1 this only suppresses the boot
+// broadcast — the CEC plugin can still power the display on/off on demand.
+//
+// Managed block pattern mirrors applyDisablePiRTCBlock above: strip every
+// prior copy (including truncated), remember first insertion point, and
+// re-insert ahead of the cape variant block to avoid leapfrog reboot loops.
+static const std::string HDMI_CEC_BLOCK_BEGIN = "# FPP HDMI CEC - BEGIN (managed by fppinit, do not edit)";
+static const std::string HDMI_CEC_BLOCK_END = "# FPP HDMI CEC - END";
+
+// --- BEGIN applyDisableHDMICECBlock ---
+static bool applyDisableHDMICECBlock(std::string& content, bool disable) {
+    const std::string orig = content;
+    std::string desired;
+    if (disable) {
+        desired = HDMI_CEC_BLOCK_BEGIN + "\n[all]\nhdmi_ignore_cec_init=1\n[all]\n" + HDMI_CEC_BLOCK_END + "\n";
+    }
+
+    size_t at = std::string::npos;
+    size_t begin = content.find(HDMI_CEC_BLOCK_BEGIN);
+    while (begin != std::string::npos) {
+        if (at == std::string::npos) {
+            at = begin;
+        }
+        size_t end = content.find(HDMI_CEC_BLOCK_END, begin);
+        end = (end == std::string::npos) ? content.length()
+                                         : end + HDMI_CEC_BLOCK_END.length();
+        if (end < content.length() && content[end] == '\n') {
+            ++end;
+        }
+        content.erase(begin, end - begin);
+        begin = content.find(HDMI_CEC_BLOCK_BEGIN);
+    }
+
+    if (!desired.empty()) {
+        if (at == std::string::npos) {
+            at = content.find(CAPE_VARIANT_BLOCK_BEGIN);
+            if (at == std::string::npos) {
+                while (!content.empty() && content.back() == '\n') {
+                    content.pop_back();
+                }
+                content += "\n\n";
+                at = content.length();
+            } else {
+                desired += "\n";
+            }
+        }
+        content.insert(at, desired);
+    }
+    return content != orig;
+}
+// --- END applyDisableHDMICECBlock ---
+#endif
+
+void setupHDMICECConfig(bool rebootIfChanged) {
+#ifdef PLATFORM_PI
+    std::string content = GetFileContents("/boot/firmware/config.txt");
+    if (content.empty()) {
+        return;
+    }
+    // Pi 5 has no firmware HDMI path (RP1/KMS), so hdmi_ignore_cec_init is
+    // ignored. Never write the block on Pi 5; this also cleans up a stale
+    // block left from when the setting previously defaulted to on.
+    bool want = !isPi5() && getRawSettingInt("DisableHDMICECInit", 0) != 0;
+    if (applyDisableHDMICECBlock(content, want)) {
+        PutFileContents("/boot/firmware/config.txt", content);
+        printf("FPP - HDMI CEC configuration changed in config.txt\n");
+        if (rebootIfChanged) {
+            printf("\n\nRebooting to load new settings.\n\n");
+            exec("/usr/sbin/reboot");
+        }
+    }
+#endif
+}
+
 void setupChannelOutputs() {
 #ifdef PLATFORM_PI
     bool hasDPI = false;

www/common/settings.php

@@ -462,6 +462,11 @@ function ApplySetting($setting, $value)
             // "reboot": 1, so the UI is already prompting for that.
             exec("sudo " . $settings['fppDir'] . "/src/fppinit setupPiRTC", $output);
             break;
+        case 'DisableHDMICECInit':
+            // fppinit owns the config.txt block. The setting is declared
+            // "reboot": 1, so the UI already prompts for reboot.
+            exec("sudo " . $settings['fppDir'] . "/src/fppinit setupHDMICEC", $output);
+            break;
         case 'screensaver':
             SetupScreenBlanking($value);
             break;

www/help/settings-system.php

@@ -11,6 +11,7 @@
     <li><b>GPIO 14 Fan Control</b> (checkbox, Raspberry Pi, Advanced) — Uses GPIO 14 PWM to control a cooling fan. Takes effect on reboot; the fan’s temperatures are then set under <b>Fan Temperatures</b> below. A cape that declares its own fan in its device tree does not use this setting and removes it.</li>
     <li><b>Fan Temperatures</b> (dynamic section, shown only when a fan thermal zone is present) — Every thermal zone with a fan cooling device bound to it — from the setting above, a cape’s own device tree, or the Pi 5 active cooler — is rendered by <code>PrintFanThermalSettings()</code> as <code>FanTrip_&lt;zone sanitized&gt;_&lt;index&gt;</code> inputs, per zone (e.g. CPU, K16-Pro) with trip points sorted low→high (“Fan On Temperature”, “Fan Speed 2/3…”). Changes are written to sysfs immediately and re-applied at every boot by <code>FPPINIT_Config</code>, since trip points revert to their device tree values on boot. <b>Reset to Defaults</b> POSTs <code>api/settings/fanThermal/reset</code> to restore the hardware values. Stored in °C, displayed in °F when <i>Temperature display units = Fahrenheit</i>.</li>
     <li><b>Status Display</b> (dropdown via <code>/dev/i2c-*</code> check) — OLED/LCD on the Pi/BeagleBone I²C bus. Options: Disabled, 128×64 SSD1306 (normal/flipped/h-flipped), 128×64 2-color variants, 128×32 variants, SH1106/SH1107, SSD1327, PCF8574/PCF8574A 16×2/20×4 I²C LCDs, etc. <i>Reboot required.</i></li>
+    <li><b>Prevent HDMI CEC at Boot</b> (checkbox, Raspberry Pi except Pi 5) — Suppresses the initial CEC Active Source broadcast at boot that can wake connected TVs/projectors (e.g. Epson L210SF after a power outage, issue #2938). When enabled, <code>fppinit</code> adds <code>hdmi_ignore_cec_init=1</code> inside a managed block in <code>/boot/firmware/config.txt</code>. Unlike <code>hdmi_ignore_cec=1</code> it only suppresses the boot broadcast — the CEC plugin can still power the display on/off on demand. Hidden on Pi 5 (KMS/RP1, no firmware HDMI path) and any stale block is removed there. <i>Reboot required.</i></li>
     <li><b>FPPD Boot Delay</b> (dropdown) — Wait after boot before starting <code>fppd</code> so slow switches/routers can come up and E1.31 multicast works. Options: 0–10s, 15/20/25/30s, 1/2/3/5 min, <b>Auto</b> (−1, wait until NTP/RTC time is valid or 5 min max). Not shown inside containers.</li>
     <li><b>Override UUID</b> (text, Advanced, pii) — Replacement UUID for FPP Connect dedup / stats / services instead of the CPU/serial-derived one. <i>Reboot required.</i></li>
 </ul>

www/settings.json

@@ -321,6 +321,7 @@
 			"description": "System Settings",
 			"settings": [
 				"GPIOFan",
+				"DisableHDMICECInit",
 				"LEDDisplayType",
 				"bootDelay",
 				"FPP_UUID"
@@ -1630,6 +1631,23 @@
 			],
 			"type": "checkbox"
 		},
+		"DisableHDMICECInit": {
+			"name": "DisableHDMICECInit",
+			"description": "Prevent HDMI CEC at Boot",
+			"gatherStats": true,
+			"tip": "When enabled, adds hdmi_ignore_cec_init=1 to config.txt to suppress the initial CEC Active Source that wakes projectors/TVs at boot (e.g. after a power outage). CEC control via the CEC plugin still works. Not applicable on Pi 5 (kernel KMS, no firmware HDMI).",
+			"reboot": 1,
+			"platforms": [
+				"Raspberry Pi"
+			],
+			"variants": {
+				"Raspberry Pi": [
+					"!Pi 5"
+				]
+			},
+			"type": "checkbox",
+			"default": "0"
+		},
 		"GPIOFan": {
 			"name": "GPIOFan",
 			"description": "GPIO 14 Fan Control",