Retry DMI operations when BUSY status returned in WCH-Link driver

src/DebugToolDrivers/WCH/Protocols/WchLink/WchLinkInterface.cpp

@@ -1,6 +1,7 @@
 #include "WchLinkInterface.hpp"
 
 #include <cassert>
+#include <thread>
 
 #include "Commands/Control/GetDeviceInfo.hpp"
 #include "Commands/Control/AttachTarget.hpp"
@@ -79,15 +80,29 @@ namespace DebugToolDrivers::Wch::Protocols::WchLink
     DebugModule::RegisterValue WchLinkInterface::readDebugModuleRegister(DebugModule::RegisterAddress address) {
         using DebugModule::DmiOperationStatus;
 
+        auto attempt = std::uint8_t{0};
+        while (attempt < WchLinkInterface::DMI_OP_MAX_RETRY) {
+            if (attempt > 0) {
+                std::this_thread::sleep_for(this->dmiOpRetryDelay);
+            }
+
             const auto response = this->sendCommandAndWaitForResponse(
                 Commands::DebugModuleInterfaceOperation{DmiOperation::READ, address}
             );
 
-        if (response.operationStatus != DmiOperationStatus::SUCCESS) {
+            if (response.operationStatus == DmiOperationStatus::SUCCESS) {
+                return response.value;
+            }
+
+            if (response.operationStatus == DmiOperationStatus::FAILED) {
                 throw Exceptions::DeviceCommunicationFailure{"DMI operation failed"};
             }
 
-        return response.value;
+            // Busy response...
+            ++attempt;
+        }
+
+        throw Exceptions::DeviceCommunicationFailure{"DMI operation timed out"};
     }
 
     void WchLinkInterface::writeDebugModuleRegister(
@@ -96,13 +111,29 @@ namespace DebugToolDrivers::Wch::Protocols::WchLink
     ) {
         using DebugModule::DmiOperationStatus;
 
+        auto attempt = std::uint8_t{0};
+        while (attempt < WchLinkInterface::DMI_OP_MAX_RETRY) {
+            if (attempt > 0) {
+                std::this_thread::sleep_for(this->dmiOpRetryDelay);
+            }
+
             const auto response = this->sendCommandAndWaitForResponse(
                 Commands::DebugModuleInterfaceOperation{DmiOperation::WRITE, address, value}
             );
 
-        if (response.operationStatus != DmiOperationStatus::SUCCESS) {
+            if (response.operationStatus == DmiOperationStatus::SUCCESS) {
+                return;
+            }
+
+            if (response.operationStatus == DmiOperationStatus::FAILED) {
                 throw Exceptions::DeviceCommunicationFailure{"DMI operation failed"};
             }
+
+            // Busy response...
+            ++attempt;
+        }
+
+        throw Exceptions::DeviceCommunicationFailure{"DMI operation timed out"};
     }
 
     void WchLinkInterface::writeFlashMemory(

src/DebugToolDrivers/WCH/Protocols/WchLink/WchLinkInterface.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <memory>
+#include <chrono>
 #include <optional>
 #include <vector>
 #include <utility>
@@ -61,11 +62,14 @@ namespace DebugToolDrivers::Wch::Protocols::WchLink
         static constexpr std::uint8_t USB_COMMAND_ENDPOINT_OUT = 0x01;
         static constexpr std::uint8_t USB_DATA_ENDPOINT_IN = 0x82;
         static constexpr std::uint8_t USB_DATA_ENDPOINT_OUT = 0x02;
+        static constexpr std::uint8_t DMI_OP_MAX_RETRY = 10;
 
         Usb::UsbInterface& usbInterface;
 
         std::uint16_t commandEndpointMaxPacketSize = 0;
         std::uint16_t dataEndpointMaxPacketSize = 0;
+        // TODO: Move this into a config param
+        std::chrono::microseconds dmiOpRetryDelay = std::chrono::microseconds{10};
 
         /**
          * The 'target activation' command returns a payload of 5 bytes.