Make solo half of split keyboards (more) usable. (#13523)

* Make solo half of split keyboards (more) usable.

Using only one half of a split keyboard (that's using the split_common
framework to communicate) is not a great experience, since several read
timeouts per scan cycle cause an unusably slow scan rate.

This change blocks all split communication attempts for 500 ms
(configurable) after an error occurs, causing the scan rate to become at
least _more_ usable, but might need some tweaking to work fully on most
keyboards. One read timeout still needs to occur after the 500 ms has
passed, and if that timeout isn't low enough, some scan cycles may still
be too slow.

* Fix lint complaint.

* Require 25 consecutive comm errors to see comms as disconnected.

The number of max errors can be overridden by defining
`SPLIT_MAX_CONNECTION_ERRORS`.

* Add comments to new defines, and ability to disable disconnection check.

Also increase `SPLIT_MAX_CONNECTION_ERRORS` to 40, since it's divisible
by most relevant numbers for the description.

* Make lint happy ...again

* Only update `connection_check_timer` when needed.

* Add new defines to split keyboard documentation.

* Move connection timeout logic to transport.c, add `is_transport_connected`.

* Use split_common disconnection logic in matrix.c.

Instead of doing more or less the same thing twice.

* Move disconnection logic to `transport_master`.

Is a cleaner implementation, and causes the scan rate while disconnected
to increase instead of decrease.

* Lint fixes.

* Lower default `SERIAL_USART_TIMEOUT` to 20 ms.

The read timeout must be low enough to not cause exessively long scan
cycles when using a solo split half. 10 ms was determined from testing
to work fine even with the slowest defined baudrate of 19200 (5 ms was
too low for that case), so 20 ms should be fine for most cases.

* Remove `SERIAL_USART_TIMEOUT` from ergodox_infinity/config.h

Was somewhat mistakenly included in an earlier PR.

* Fix building with `USE_I2C`.

* Reduce built firmware size.

Not really sure why this works, the idea was taken from tzarc's work on
split disconnection.

* Tweak and improve opt-out for split disconnection logic.

There are now two ways to opt out from this feature:
* Set `SPLIT_MAX_CONNECTION_ERRORS` to 0. This will completely disable
  the connection status checks (also affects the slave matrix reset logic in
  matrix.c, though).
* Set `SPLIT_CONNECTION_CHECK_TIMEOUT` to 0. This will only disable the
  communication throttling while disconnected. Will make the firmware
  smaller.

* Make split disconnection logic work with custom transports.

Includes a fallback implementation for keyboards using a custom
split_util.c but not a custom matrix.c (currently no such keyboard seems
to be merged, though).

* Remove unnecessary include of timer.h

Co-authored-by: Joel Challis <git@zvecr.com>

Co-authored-by: Joel Challis <git@zvecr.com>

5 files changed, 123 insertions, 73 deletions

diff --git a/quantum/matrix.c b/quantum/matrix.c
index d22817bf48..33586c431b 100644
--- a/quantum/matrix.c
+++ b/quantum/matrix.c
@@ -25,10 +25,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    include "split_common/split_util.h"
 #    include "split_common/transactions.h"
 
-#    ifndef ERROR_DISCONNECT_COUNT
-#        define ERROR_DISCONNECT_COUNT 5
-#    endif  // ERROR_DISCONNECT_COUNT
-
 #    define ROWS_PER_HAND (MATRIX_ROWS / 2)
 #else
 #    define ROWS_PER_HAND (MATRIX_ROWS)
@@ -307,33 +303,31 @@ void matrix_init(void) {
 }
 
 #ifdef SPLIT_KEYBOARD
+// Fallback implementation for keyboards not using the standard split_util.c
+__attribute__((weak)) bool transport_master_if_connected(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+    transport_master(master_matrix, slave_matrix);
+    return true;  // Treat the transport as always connected
+}
+
 bool matrix_post_scan(void) {
     bool changed = false;
     if (is_keyboard_master()) {
-        static uint8_t error_count;
-
         matrix_row_t slave_matrix[ROWS_PER_HAND] = {0};
-        if (!transport_master(matrix + thisHand, slave_matrix)) {
-            error_count++;
-
-            if (error_count > ERROR_DISCONNECT_COUNT) {
-                // reset other half if disconnected
-                for (int i = 0; i < ROWS_PER_HAND; ++i) {
-                    matrix[thatHand + i] = 0;
-                    slave_matrix[i]      = 0;
-                }
-
-                changed = true;
-            }
-        } else {
-            error_count = 0;
-
+        if (transport_master_if_connected(matrix + thisHand, slave_matrix)) {
             for (int i = 0; i < ROWS_PER_HAND; ++i) {
                 if (matrix[thatHand + i] != slave_matrix[i]) {
                     matrix[thatHand + i] = slave_matrix[i];
                     changed              = true;
                 }
             }
+        } else {
+            // reset other half if disconnected
+            for (int i = 0; i < ROWS_PER_HAND; ++i) {
+                matrix[thatHand + i] = 0;
+                slave_matrix[i]      = 0;
+            }
+
+            changed = true;
         }
 
         matrix_scan_quantum();
diff --git a/quantum/split_common/split_util.c b/quantum/split_common/split_util.c
index 8d414f6fe6..35f0a9d181 100644
--- a/quantum/split_common/split_util.c
+++ b/quantum/split_common/split_util.c
@@ -39,6 +39,21 @@
 #    define SPLIT_USB_TIMEOUT_POLL 10
 #endif
 
+// Max number of consecutive failed communications (one per scan cycle) before the communication is seen as disconnected.
+// Set to 0 to disable the disconnection check altogether.
+#ifndef SPLIT_MAX_CONNECTION_ERRORS
+#    define SPLIT_MAX_CONNECTION_ERRORS 10
+#endif  // SPLIT_MAX_CONNECTION_ERRORS
+
+// How long (in milliseconds) to block all connection attempts after the communication has been flagged as disconnected.
+// One communication attempt will be allowed everytime this amount of time has passed since the last attempt. If that attempt succeeds, the communication is seen as working again.
+// Set to 0 to disable communication throttling while disconnected
+#ifndef SPLIT_CONNECTION_CHECK_TIMEOUT
+#    define SPLIT_CONNECTION_CHECK_TIMEOUT 500
+#endif  // SPLIT_CONNECTION_CHECK_TIMEOUT
+
+static uint8_t connection_errors = 0;
+
 volatile bool isLeftHand = true;
 
 #if defined(SPLIT_USB_DETECT)
@@ -142,3 +157,39 @@ void split_post_init(void) {
         transport_slave_init();
     }
 }
+
+bool is_transport_connected(void) { return connection_errors < SPLIT_MAX_CONNECTION_ERRORS; }
+
+bool transport_master_if_connected(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
+#if SPLIT_MAX_CONNECTION_ERRORS > 0 && SPLIT_CONNECTION_CHECK_TIMEOUT > 0
+    // Throttle transaction attempts if target doesn't seem to be connected
+    // Without this, a solo half becomes unusable due to constant read timeouts
+    static uint16_t connection_check_timer = 0;
+    const bool      is_disconnected        = !is_transport_connected();
+    if (is_disconnected && timer_elapsed(connection_check_timer) < SPLIT_CONNECTION_CHECK_TIMEOUT) {
+        return false;
+    }
+#endif  // SPLIT_MAX_CONNECTION_ERRORS > 0 && SPLIT_CONNECTION_CHECK_TIMEOUT > 0
+
+    __attribute__((unused)) bool okay = transport_master(master_matrix, slave_matrix);
+#if SPLIT_MAX_CONNECTION_ERRORS > 0
+    if (!okay) {
+        if (connection_errors < UINT8_MAX) {
+            connection_errors++;
+        }
+#    if SPLIT_CONNECTION_CHECK_TIMEOUT > 0
+        bool connected = is_transport_connected();
+        if (!connected) {
+            connection_check_timer = timer_read();
+            dprintln("Target disconnected, throttling connection attempts");
+        }
+        return connected;
+    } else if (is_disconnected) {
+        dprintln("Target connected");
+#    endif  // SPLIT_CONNECTION_CHECK_TIMEOUT > 0
+    }
+
+    connection_errors = 0;
+#endif  // SPLIT_MAX_CONNECTION_ERRORS > 0
+    return true;
+}
diff --git a/quantum/split_common/split_util.h b/quantum/split_common/split_util.h
index a4c12519e0..ef72043bb7 100644
--- a/quantum/split_common/split_util.h
+++ b/quantum/split_common/split_util.h
@@ -5,8 +5,13 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "matrix.h"
+
 extern volatile bool isLeftHand;
 
 void matrix_master_OLED_init(void);
 void split_pre_init(void);
 void split_post_init(void);
+
+bool transport_master_if_connected(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]);
+bool is_transport_connected(void);
diff --git a/quantum/split_common/transactions.c b/quantum/split_common/transactions.c
index 7eb3eca3e7..28ea4ef6d8 100644
--- a/quantum/split_common/transactions.c
+++ b/quantum/split_common/transactions.c
@@ -23,6 +23,7 @@
 #include "quantum.h"
 #include "transactions.h"
 #include "transport.h"
+#include "split_util.h"
 #include "transaction_id_define.h"
 
 #define SYNC_TIMER_OFFSET 2
@@ -53,34 +54,30 @@ void slave_rpc_exec_callback(uint8_t initiator2target_buffer_size, const void *i
 ////////////////////////////////////////////////////
 // Helpers
 
-bool transaction_handler_master(bool okay, matrix_row_t master_matrix[], matrix_row_t slave_matrix[], const char *prefix, bool (*handler)(matrix_row_t master_matrix[], matrix_row_t slave_matrix[])) {
-    if (okay) {
-        bool this_okay = true;
-        for (int iter = 1; iter <= 10; ++iter) {
-            if (!this_okay) {
-                for (int i = 0; i < iter * iter; ++i) {
-                    wait_us(10);
-                }
+static bool transaction_handler_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[], const char *prefix, bool (*handler)(matrix_row_t master_matrix[], matrix_row_t slave_matrix[])) {
+    int num_retries = is_transport_connected() ? 10 : 1;
+    for (int iter = 1; iter <= num_retries; ++iter) {
+        if (iter > 1) {
+            for (int i = 0; i < iter * iter; ++i) {
+                wait_us(10);
             }
-            ATOMIC_BLOCK_FORCEON { this_okay = handler(master_matrix, slave_matrix); };
-            if (this_okay) break;
-        }
-        okay &= this_okay;
-        if (!okay) {
-            dprintf("Failed to execute %s\n", prefix);
         }
+        bool this_okay = true;
+        ATOMIC_BLOCK_FORCEON { this_okay = handler(master_matrix, slave_matrix); };
+        if (this_okay) return true;
     }
-    return okay;
+    dprintf("Failed to execute %s\n", prefix);
+    return false;
 }
 
-#define TRANSACTION_HANDLER_MASTER(prefix)                                                                \
-    do {                                                                                                  \
-        okay &= transaction_handler_master(okay, master_matrix, slave_matrix, #prefix, &prefix##_master); \
+#define TRANSACTION_HANDLER_MASTER(prefix)                                                                              \
+    do {                                                                                                                \
+        if (!transaction_handler_master(master_matrix, slave_matrix, #prefix, &prefix##_handlers_master)) return false; \
     } while (0)
 
-#define TRANSACTION_HANDLER_SLAVE(prefix)                                      \
-    do {                                                                       \
-        ATOMIC_BLOCK_FORCEON { prefix##_slave(master_matrix, slave_matrix); }; \
+#define TRANSACTION_HANDLER_SLAVE(prefix)                                               \
+    do {                                                                                \
+        ATOMIC_BLOCK_FORCEON { prefix##_handlers_slave(master_matrix, slave_matrix); }; \
     } while (0)
 
 inline static bool read_if_checksum_mismatch(int8_t trans_id_checksum, int8_t trans_id_retrieve, uint32_t *last_update, void *destination, const void *equiv_shmem, size_t length) {
@@ -138,8 +135,8 @@ static void slave_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_row
 }
 
 // clang-format off
-#define TRANSACTIONS_SLAVE_MATRIX_MASTER() TRANSACTION_HANDLER_MASTER(slave_matrix_handlers)
-#define TRANSACTIONS_SLAVE_MATRIX_SLAVE() TRANSACTION_HANDLER_SLAVE(slave_matrix_handlers)
+#define TRANSACTIONS_SLAVE_MATRIX_MASTER() TRANSACTION_HANDLER_MASTER(slave_matrix)
+#define TRANSACTIONS_SLAVE_MATRIX_SLAVE() TRANSACTION_HANDLER_SLAVE(slave_matrix)
 #define TRANSACTIONS_SLAVE_MATRIX_REGISTRATIONS \
     [GET_SLAVE_MATRIX_CHECKSUM] = trans_target2initiator_initializer(smatrix.checksum), \
     [GET_SLAVE_MATRIX_DATA]     = trans_target2initiator_initializer(smatrix.matrix),
@@ -160,8 +157,8 @@ static void master_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_ro
     memcpy(master_matrix, split_shmem->mmatrix.matrix, sizeof(split_shmem->mmatrix.matrix));
 }
 
-#    define TRANSACTIONS_MASTER_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(master_matrix_handlers)
-#    define TRANSACTIONS_MASTER_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(master_matrix_handlers)
+#    define TRANSACTIONS_MASTER_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(master_matrix)
+#    define TRANSACTIONS_MASTER_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(master_matrix)
 #    define TRANSACTIONS_MASTER_MATRIX_REGISTRATIONS [PUT_MASTER_MATRIX] = trans_initiator2target_initializer(mmatrix.matrix),
 
 #else  // SPLIT_TRANSPORT_MIRROR
@@ -196,8 +193,8 @@ static void encoder_handlers_slave(matrix_row_t master_matrix[], matrix_row_t sl
 }
 
 // clang-format off
-#    define TRANSACTIONS_ENCODERS_MASTER() TRANSACTION_HANDLER_MASTER(encoder_handlers)
-#    define TRANSACTIONS_ENCODERS_SLAVE() TRANSACTION_HANDLER_SLAVE(encoder_handlers)
+#    define TRANSACTIONS_ENCODERS_MASTER() TRANSACTION_HANDLER_MASTER(encoder)
+#    define TRANSACTIONS_ENCODERS_SLAVE() TRANSACTION_HANDLER_SLAVE(encoder)
 #    define TRANSACTIONS_ENCODERS_REGISTRATIONS \
     [GET_ENCODERS_CHECKSUM] = trans_target2initiator_initializer(encoders.checksum), \
     [GET_ENCODERS_DATA]     = trans_target2initiator_initializer(encoders.state),
@@ -238,8 +235,8 @@ static void sync_timer_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     }
 }
 
-#    define TRANSACTIONS_SYNC_TIMER_MASTER()      TRANSACTION_HANDLER_MASTER(sync_timer_handlers)
-#    define TRANSACTIONS_SYNC_TIMER_SLAVE()       TRANSACTION_HANDLER_SLAVE(sync_timer_handlers)
+#    define TRANSACTIONS_SYNC_TIMER_MASTER()      TRANSACTION_HANDLER_MASTER(sync_timer)
+#    define TRANSACTIONS_SYNC_TIMER_SLAVE()       TRANSACTION_HANDLER_SLAVE(sync_timer)
 #    define TRANSACTIONS_SYNC_TIMER_REGISTRATIONS [PUT_SYNC_TIMER] = trans_initiator2target_initializer(sync_timer),
 
 #else  // DISABLE_SYNC_TIMER
@@ -272,8 +269,8 @@ static void layer_state_handlers_slave(matrix_row_t master_matrix[], matrix_row_
 }
 
 // clang-format off
-#    define TRANSACTIONS_LAYER_STATE_MASTER() TRANSACTION_HANDLER_MASTER(layer_state_handlers)
-#    define TRANSACTIONS_LAYER_STATE_SLAVE() TRANSACTION_HANDLER_SLAVE(layer_state_handlers)
+#    define TRANSACTIONS_LAYER_STATE_MASTER() TRANSACTION_HANDLER_MASTER(layer_state)
+#    define TRANSACTIONS_LAYER_STATE_SLAVE() TRANSACTION_HANDLER_SLAVE(layer_state)
 #    define TRANSACTIONS_LAYER_STATE_REGISTRATIONS \
     [PUT_LAYER_STATE]         = trans_initiator2target_initializer(layers.layer_state), \
     [PUT_DEFAULT_LAYER_STATE] = trans_initiator2target_initializer(layers.default_layer_state),
@@ -303,8 +300,8 @@ static void led_state_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     set_split_host_keyboard_leds(split_shmem->led_state);
 }
 
-#    define TRANSACTIONS_LED_STATE_MASTER()      TRANSACTION_HANDLER_MASTER(led_state_handlers)
-#    define TRANSACTIONS_LED_STATE_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_state_handlers)
+#    define TRANSACTIONS_LED_STATE_MASTER()      TRANSACTION_HANDLER_MASTER(led_state)
+#    define TRANSACTIONS_LED_STATE_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_state)
 #    define TRANSACTIONS_LED_STATE_REGISTRATIONS [PUT_LED_STATE] = trans_initiator2target_initializer(led_state),
 
 #else  // SPLIT_LED_STATE_ENABLE
@@ -360,8 +357,8 @@ static void mods_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave
 #    endif
 }
 
-#    define TRANSACTIONS_MODS_MASTER()      TRANSACTION_HANDLER_MASTER(mods_handlers)
-#    define TRANSACTIONS_MODS_SLAVE()       TRANSACTION_HANDLER_SLAVE(mods_handlers)
+#    define TRANSACTIONS_MODS_MASTER()      TRANSACTION_HANDLER_MASTER(mods)
+#    define TRANSACTIONS_MODS_SLAVE()       TRANSACTION_HANDLER_SLAVE(mods)
 #    define TRANSACTIONS_MODS_REGISTRATIONS [PUT_MODS] = trans_initiator2target_initializer(mods),
 
 #else  // SPLIT_MODS_ENABLE
@@ -385,8 +382,8 @@ static bool backlight_handlers_master(matrix_row_t master_matrix[], matrix_row_t
 
 static void backlight_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { backlight_set(split_shmem->backlight_level); }
 
-#    define TRANSACTIONS_BACKLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(backlight_handlers)
-#    define TRANSACTIONS_BACKLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(backlight_handlers)
+#    define TRANSACTIONS_BACKLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(backlight)
+#    define TRANSACTIONS_BACKLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(backlight)
 #    define TRANSACTIONS_BACKLIGHT_REGISTRATIONS [PUT_BACKLIGHT] = trans_initiator2target_initializer(backlight_level),
 
 #else  // BACKLIGHT_ENABLE
@@ -422,8 +419,8 @@ static void rgblight_handlers_slave(matrix_row_t master_matrix[], matrix_row_t s
     }
 }
 
-#    define TRANSACTIONS_RGBLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(rgblight_handlers)
-#    define TRANSACTIONS_RGBLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgblight_handlers)
+#    define TRANSACTIONS_RGBLIGHT_MASTER()      TRANSACTION_HANDLER_MASTER(rgblight)
+#    define TRANSACTIONS_RGBLIGHT_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgblight)
 #    define TRANSACTIONS_RGBLIGHT_REGISTRATIONS [PUT_RGBLIGHT] = trans_initiator2target_initializer(rgblight_sync),
 
 #else  // defined(RGBLIGHT_ENABLE) && defined(RGBLIGHT_SPLIT)
@@ -452,8 +449,8 @@ static void led_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     led_matrix_set_suspend_state(split_shmem->led_matrix_sync.led_suspend_state);
 }
 
-#    define TRANSACTIONS_LED_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(led_matrix_handlers)
-#    define TRANSACTIONS_LED_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_matrix_handlers)
+#    define TRANSACTIONS_LED_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(led_matrix)
+#    define TRANSACTIONS_LED_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(led_matrix)
 #    define TRANSACTIONS_LED_MATRIX_REGISTRATIONS [PUT_LED_MATRIX] = trans_initiator2target_initializer(led_matrix_sync),
 
 #else  // defined(LED_MATRIX_ENABLE) && defined(LED_MATRIX_SPLIT)
@@ -482,8 +479,8 @@ static void rgb_matrix_handlers_slave(matrix_row_t master_matrix[], matrix_row_t
     rgb_matrix_set_suspend_state(split_shmem->rgb_matrix_sync.rgb_suspend_state);
 }
 
-#    define TRANSACTIONS_RGB_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(rgb_matrix_handlers)
-#    define TRANSACTIONS_RGB_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgb_matrix_handlers)
+#    define TRANSACTIONS_RGB_MATRIX_MASTER()      TRANSACTION_HANDLER_MASTER(rgb_matrix)
+#    define TRANSACTIONS_RGB_MATRIX_SLAVE()       TRANSACTION_HANDLER_SLAVE(rgb_matrix)
 #    define TRANSACTIONS_RGB_MATRIX_REGISTRATIONS [PUT_RGB_MATRIX] = trans_initiator2target_initializer(rgb_matrix_sync),
 
 #else  // defined(RGB_MATRIX_ENABLE) && defined(RGB_MATRIX_SPLIT)
@@ -507,8 +504,8 @@ static bool wpm_handlers_master(matrix_row_t master_matrix[], matrix_row_t slave
 
 static void wpm_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { set_current_wpm(split_shmem->current_wpm); }
 
-#    define TRANSACTIONS_WPM_MASTER()      TRANSACTION_HANDLER_MASTER(wpm_handlers)
-#    define TRANSACTIONS_WPM_SLAVE()       TRANSACTION_HANDLER_SLAVE(wpm_handlers)
+#    define TRANSACTIONS_WPM_MASTER()      TRANSACTION_HANDLER_MASTER(wpm)
+#    define TRANSACTIONS_WPM_SLAVE()       TRANSACTION_HANDLER_SLAVE(wpm)
 #    define TRANSACTIONS_WPM_REGISTRATIONS [PUT_WPM] = trans_initiator2target_initializer(current_wpm),
 
 #else  // defined(WPM_ENABLE) && defined(SPLIT_WPM_ENABLE)
@@ -538,8 +535,8 @@ static void oled_handlers_slave(matrix_row_t master_matrix[], matrix_row_t slave
     }
 }
 
-#    define TRANSACTIONS_OLED_MASTER()      TRANSACTION_HANDLER_MASTER(oled_handlers)
-#    define TRANSACTIONS_OLED_SLAVE()       TRANSACTION_HANDLER_SLAVE(oled_handlers)
+#    define TRANSACTIONS_OLED_MASTER()      TRANSACTION_HANDLER_MASTER(oled)
+#    define TRANSACTIONS_OLED_SLAVE()       TRANSACTION_HANDLER_SLAVE(oled)
 #    define TRANSACTIONS_OLED_REGISTRATIONS [PUT_OLED] = trans_initiator2target_initializer(current_oled_state),
 
 #else  // defined(OLED_DRIVER_ENABLE) && defined(SPLIT_OLED_ENABLE)
@@ -569,8 +566,8 @@ static void st7565_handlers_slave(matrix_row_t master_matrix[], matrix_row_t sla
     }
 }
 
-#    define TRANSACTIONS_ST7565_MASTER()      TRANSACTION_HANDLER_MASTER(st7565_handlers)
-#    define TRANSACTIONS_ST7565_SLAVE()       TRANSACTION_HANDLER_SLAVE(st7565_handlers)
+#    define TRANSACTIONS_ST7565_MASTER()      TRANSACTION_HANDLER_MASTER(st7565)
+#    define TRANSACTIONS_ST7565_SLAVE()       TRANSACTION_HANDLER_SLAVE(st7565)
 #    define TRANSACTIONS_ST7565_REGISTRATIONS [PUT_ST7565] = trans_initiator2target_initializer(current_st7565_state),
 
 #else  // defined(ST7565_ENABLE) && defined(SPLIT_ST7565_ENABLE)
@@ -618,7 +615,6 @@ split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
 };
 
 bool transactions_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
-    bool okay = true;
     TRANSACTIONS_SLAVE_MATRIX_MASTER();
     TRANSACTIONS_MASTER_MATRIX_MASTER();
     TRANSACTIONS_ENCODERS_MASTER();
@@ -633,7 +629,7 @@ bool transactions_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix
     TRANSACTIONS_WPM_MASTER();
     TRANSACTIONS_OLED_MASTER();
     TRANSACTIONS_ST7565_MASTER();
-    return okay;
+    return true;
 }
 
 void transactions_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) {
@@ -666,6 +662,10 @@ void transaction_register_rpc(int8_t transaction_id, slave_callback_t callback)
 }
 
 bool transaction_rpc_exec(int8_t transaction_id, uint8_t initiator2target_buffer_size, const void *initiator2target_buffer, uint8_t target2initiator_buffer_size, void *target2initiator_buffer) {
+    // Prevent transaction attempts while transport is disconnected
+    if (!is_transport_connected()) {
+        return false;
+    }
     // Prevent invoking RPC on QMK core sync data
     if (transaction_id <= GET_RPC_RESP_DATA) return false;
     // Prevent sizing issues
diff --git a/quantum/split_common/transport.c b/quantum/split_common/transport.c
index a711ef85f0..bcc0261417 100644
--- a/quantum/split_common/transport.c
+++ b/quantum/split_common/transport.c
@@ -115,4 +115,4 @@ bool transport_execute_transaction(int8_t id, const void *initiator2target_buf,
 
 bool transport_master(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { return transactions_master(master_matrix, slave_matrix); }
 
-void transport_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { transactions_slave(master_matrix, slave_matrix); }
\ No newline at end of file
+void transport_slave(matrix_row_t master_matrix[], matrix_row_t slave_matrix[]) { transactions_slave(master_matrix, slave_matrix); }