From 11e4b62438e02bf8a9d914c8b6e8d8de6d2e6b3c Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 29 Apr 2021 15:12:58 +1000
Subject: [PATCH] SRV_Channel: allow build with no channels

needed for AP_Periph when using LED driver only
---
 libraries/SRV_Channel/SRV_Channel.h       | 10 +++++++++-
 libraries/SRV_Channel/SRV_Channel_aux.cpp |  4 ++++
 libraries/SRV_Channel/SRV_Channels.cpp    |  4 ++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/libraries/SRV_Channel/SRV_Channel.h b/libraries/SRV_Channel/SRV_Channel.h
index 84bbbbddc4..783e953693 100644
--- a/libraries/SRV_Channel/SRV_Channel.h
+++ b/libraries/SRV_Channel/SRV_Channel.h
@@ -22,11 +22,15 @@
 #include <AP_SBusOut/AP_SBusOut.h>
 #include <AP_BLHeli/AP_BLHeli.h>
 
-#if !defined(NUM_SERVO_CHANNELS) && defined(HAL_BUILD_AP_PERIPH) && defined(HAL_PWM_COUNT) && (HAL_PWM_COUNT >= 1)
+#ifndef NUM_SERVO_CHANNELS
+#if defined(HAL_BUILD_AP_PERIPH) && defined(HAL_PWM_COUNT)
     #define NUM_SERVO_CHANNELS HAL_PWM_COUNT
+#elif defined(HAL_BUILD_AP_PERIPH)
+    #define NUM_SERVO_CHANNELS 0
 #else
     #define NUM_SERVO_CHANNELS 16
 #endif
+#endif
 
 class SRV_Channels;
 
@@ -475,7 +479,11 @@ public:
     static AP_HAL::RCOutput::DshotEscType get_dshot_esc_type() { return AP_HAL::RCOutput::DshotEscType(_singleton->dshot_esc_type.get()); }
 
     static SRV_Channel *srv_channel(uint8_t i) {
+#if NUM_SERVO_CHANNELS > 0
         return i<NUM_SERVO_CHANNELS?&channels[i]:nullptr;
+#else
+        return nullptr;
+#endif
     }
 
     // SERVO* parameters
diff --git a/libraries/SRV_Channel/SRV_Channel_aux.cpp b/libraries/SRV_Channel/SRV_Channel_aux.cpp
index 70682897f0..03ca964182 100644
--- a/libraries/SRV_Channel/SRV_Channel_aux.cpp
+++ b/libraries/SRV_Channel/SRV_Channel_aux.cpp
@@ -21,6 +21,10 @@
 #include <AP_HAL/AP_HAL.h>
 #include <RC_Channel/RC_Channel.h>
 
+#if NUM_SERVO_CHANNELS == 0
+#pragma GCC diagnostic ignored "-Wtype-limits"
+#endif
+
 extern const AP_HAL::HAL& hal;
 
 /// map a function to a servo channel and output it
diff --git a/libraries/SRV_Channel/SRV_Channels.cpp b/libraries/SRV_Channel/SRV_Channels.cpp
index 2caf570a08..1c83d78296 100644
--- a/libraries/SRV_Channel/SRV_Channels.cpp
+++ b/libraries/SRV_Channel/SRV_Channels.cpp
@@ -34,6 +34,10 @@
   #include <AP_PiccoloCAN/AP_PiccoloCAN.h>
 #endif
 
+#if NUM_SERVO_CHANNELS == 0
+#pragma GCC diagnostic ignored "-Wtype-limits"
+#endif
+
 extern const AP_HAL::HAL& hal;
 
 SRV_Channel *SRV_Channels::channels;