diff --git a/libraries/AP_HAL_ChibiOS/RCOutput.cpp b/libraries/AP_HAL_ChibiOS/RCOutput.cpp
index d8c5a218a2..1817c3e681 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCOutput.cpp
@@ -16,6 +16,7 @@
  * Bi-directional dshot based on Betaflight, code by Andy Piper and Siddharth Bharat Purohit
  * 
  * There really is no dshot reference. For information try these resources:
+ * https://brushlesswhoop.com/dshot-and-bidirectional-dshot/
  * https://blck.mn/2016/11/dshot-the-new-kid-on-the-block/
  * https://www.swallenhardware.io/battlebots/2019/4/20/a-developers-guide-to-dshot-escs
  */
@@ -981,10 +982,11 @@ bool RCOutput::setup_group_DMA(pwm_group &group, uint32_t bitrate, uint32_t bit_
 
 #ifdef HAL_WITH_BIDIR_DSHOT
     // configure input capture DMA if required
-    if (is_bidir_dshot_enabled()) {
+    if (is_bidir_dshot_enabled(group)) {
         if (!bdshot_setup_group_ic_DMA(group)) {
-            group.dma_handle->unlock();
-            return false;
+            _bdshot.mask &= ~group.ch_mask; // only use dshot on this group
+            _bdshot.disabled_mask |= group.ch_mask;
+            active_high = true;
         }
     }
 #endif
@@ -1115,7 +1117,7 @@ void RCOutput::set_group_mode(pwm_group &group)
     case MODE_PWM_DSHOT150 ... MODE_PWM_DSHOT1200: {
 #if HAL_DSHOT_ENABLED
         const uint32_t rate = protocol_bitrate(group.current_mode);
-        bool active_high = is_bidir_dshot_enabled() ? false : true;
+        bool active_high = is_bidir_dshot_enabled(group) ? false : true;
         bool at_least_freq = false;
         // calculate min time between pulses
         const uint32_t pulse_send_time_us = 1000000UL * dshot_bit_length / rate;
@@ -1131,7 +1133,7 @@ void RCOutput::set_group_mode(pwm_group &group)
             group.current_mode = MODE_PWM_NORMAL;
             break;
         }
-        if (is_bidir_dshot_enabled()) {
+        if (is_bidir_dshot_enabled(group)) {
             group.dshot_pulse_send_time_us = pulse_send_time_us;
             // to all intents and purposes the pulse time of send and receive are the same
             group.dshot_pulse_time_us = pulse_send_time_us + pulse_send_time_us + 30;
diff --git a/libraries/AP_HAL_ChibiOS/RCOutput.h b/libraries/AP_HAL_ChibiOS/RCOutput.h
index 0b0a41b811..037e656984 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput.h
+++ b/libraries/AP_HAL_ChibiOS/RCOutput.h
@@ -314,6 +314,8 @@ private:
     // input capture is expecting TELEM_IC_SAMPLE (16) ticks per transition (22) so the maximum
     // value of the counter in CCR registers is 16*22 == 352, so must be 16-bit
     static const uint16_t GCR_TELEMETRY_BUFFER_LEN = GCR_TELEMETRY_BIT_LEN*sizeof(dmar_uint_t);
+    static const uint16_t INVALID_ERPM = 0xffffU;
+    static const uint16_t ZERO_ERPM = 0x0fffU;
 
     struct pwm_group {
         // only advanced timers can do high clocks needed for more than 400Hz
@@ -551,6 +553,7 @@ private:
     // handling of bi-directional dshot
     struct {
         uint32_t mask;
+        uint32_t disabled_mask; // record of channels that were tried, but failed
         uint16_t erpm[max_channels];
         volatile uint32_t update_mask;
 #ifdef HAL_WITH_BIDIR_DSHOT
@@ -619,7 +622,7 @@ private:
 
     volatile bool _initialised;
 
-    bool is_bidir_dshot_enabled() const { return _bdshot.mask != 0; }
+    bool is_bidir_dshot_enabled(const pwm_group& group) const { return (_bdshot.mask & group.ch_mask) != 0; }
 
     static bool is_dshot_send_allowed(DshotState state) {
       return state == DshotState::IDLE || state == DshotState::RECV_COMPLETE || state == DshotState::RECV_FAILED;
diff --git a/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp b/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp
index 43664570eb..31a7d7f4c6 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp
@@ -58,11 +58,12 @@ void RCOutput::set_bidir_dshot_mask(uint32_t mask)
         iomcu.set_bidir_dshot_mask(mask & iomcu_mask);
     }
 #endif
-    _bdshot.mask = (mask >> chan_offset);
+    const uint32_t local_mask = (mask >> chan_offset) & ~_bdshot.disabled_mask;
+    _bdshot.mask = local_mask;
     // we now need to reconfigure the DMA channels since they are affected by the value of the mask
     for (uint8_t i = 0; i < NUM_GROUPS; i++ ) {
         pwm_group &group = pwm_group_list[i];
-        if (((group.ch_mask << chan_offset) & mask) == 0) {
+        if ((group.ch_mask & local_mask) == 0) {
             // this group is not affected
             continue;
         }
@@ -101,7 +102,7 @@ bool RCOutput::bdshot_setup_group_ic_DMA(pwm_group &group)
                                                 FUNCTOR_BIND_MEMBER(&RCOutput::bdshot_ic_dma_deallocate, void, Shared_DMA *));
             }
             if (!group.bdshot.ic_dma_handle[i]) {
-                return false;
+                goto ic_dma_fail;
             }
         }
     }
@@ -149,11 +150,11 @@ bool RCOutput::bdshot_setup_group_ic_DMA(pwm_group &group)
             if (!group.dma_ch[curr_chan].have_dma) {
                 // We can't find a DMA channel to use so
                 // return error
-                return false;
+                goto ic_dma_fail;
             }
             if (group.bdshot.ic_dma_handle[i]) {
                 INTERNAL_ERROR(AP_InternalError::error_t::dma_fail);
-                return false;
+                goto ic_dma_fail;
             }
             // share up channel if required
             if (group.dma_ch[curr_chan].stream_id == group.dma_up_stream_id) {
@@ -165,7 +166,7 @@ bool RCOutput::bdshot_setup_group_ic_DMA(pwm_group &group)
                                             FUNCTOR_BIND_MEMBER(&RCOutput::bdshot_ic_dma_deallocate, void, Shared_DMA *));
             }
             if (!group.bdshot.ic_dma_handle[i]) {
-                return false;
+                goto ic_dma_fail;
             }
             group.bdshot.telem_tim_ch[i] = curr_chan;
             group.dma_ch[i] = group.dma_ch[curr_chan];
@@ -181,6 +182,15 @@ bool RCOutput::bdshot_setup_group_ic_DMA(pwm_group &group)
     }
 
     return true;
+
+ic_dma_fail:
+    for (uint8_t i = 0; i < 4; i++) {
+        if (group.bdshot.ic_dma_handle[i] != group.dma_handle) {
+            delete group.bdshot.ic_dma_handle[i];
+        }
+        group.bdshot.ic_dma_handle[i] = nullptr;
+    }
+    return false;
 }
 
 /*
@@ -676,8 +686,6 @@ uint32_t RCOutput::bdshot_get_output_rate_hz(const enum output_mode mode)
     }
 }
 
-#define INVALID_ERPM 0xfffU
-
 // decode a telemetry packet from a GCR encoded stride buffer, take from betaflight decodeTelemetryPacket
 // see https://github.com/betaflight/betaflight/pull/8554#issuecomment-512507625 for a description of the protocol
 uint32_t RCOutput::bdshot_decode_telemetry_packet(dmar_uint_t* buffer, uint32_t count)
@@ -801,7 +809,7 @@ bool RCOutput::bdshot_decode_telemetry_from_erpm(uint16_t encodederpm, uint8_t c
 
     erpm = (1000000U * 60U / 100U + erpm / 2U) / erpm;
 
-    if (encodederpm == 0x0fff) { // the special 0 encoding
+    if (encodederpm == ZERO_ERPM) { // the special 0 encoding
         erpm = 0;
     }
 
diff --git a/libraries/AP_HAL_ChibiOS/RCOutput_iofirmware.cpp b/libraries/AP_HAL_ChibiOS/RCOutput_iofirmware.cpp
index 994485e4e9..c8d535dc5b 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput_iofirmware.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCOutput_iofirmware.cpp
@@ -353,8 +353,6 @@ void RCOutput::bdshot_config_icu_dshot_f1(stm32_tim_t* TIMx, uint8_t chan, uint8
     }
 }
 
-#define INVALID_ERPM 0xfffU
-
 // decode a telemetry packet from a GCR encoded stride buffer, take from betaflight decodeTelemetryPacket
 // see https://github.com/betaflight/betaflight/pull/8554#issuecomment-512507625 for a description of the protocol
 uint32_t RCOutput::bdshot_decode_telemetry_packet_f1(dmar_uint_t* buffer, uint32_t count, bool reversed)