Correct CSR pipe behaviour when StallFree is used

include/acl.h

@@ -542,6 +542,9 @@ struct acl_hostpipe_mapping {
 
   int protocol = -1; // avalon_streaming = 0, avalon_streaming_uses_ready = 1
                      // avalon_mm = 2, avalon_mm_uses_ready = 3
+
+  // Introduced in 2024.2
+  int is_stall_free = -1; // -1 means unset, set value is 0 or 1;
 };
 
 // Mapping of sideband signals to logical pipe

include/acl_types.h

@@ -349,6 +349,9 @@ typedef struct host_pipe_struct {
   // Sideband signals vector
   std::vector<sideband_signal_t> side_band_signals_vector;
 
+  // Introduced in 2024.2
+  int is_stall_free = -1; // -1 means unset, set value is 0 or 1;
+
 } host_pipe_t;
 
 // The device-specific information about a program.

src/acl_auto_configure.cpp

@@ -663,11 +663,21 @@ static bool read_hostpipe_mappings(
 
     // Start from 2024.0, there is a new field called protocol in the
     // auto-discovery string
+    // This field isn't currently being used by the Runtime.
+    // It is reserved for the future when new protocols are
+    // supported and the Runtime needs to differentiate.
     if (result && counters.back() > 0) {
       result = result && read_int_counters(config_str, curr_pos,
                                            mapping.protocol, counters);
     }
 
+    // Start from 2024.2, there is a new field called is_stall_free in the
+    // auto-discovery string
+    if (result && counters.back() > 0) {
+      result = result && read_int_counters(config_str, curr_pos,
+                                           mapping.is_stall_free, counters);
+    }
+
     hostpipe_mappings.emplace_back(mapping);
 
     while (result && counters.back() > 0) {

src/acl_hostch.cpp

@@ -823,9 +823,24 @@ void acl_read_program_hostpipe(void *user_data, acl_device_op_t *op) {
   acl_set_device_op_execution_status(op, CL_RUNNING);
 
   if (host_pipe_info.implement_in_csr) {
-    // CSR read, currently only blocking version is implemented
+    // Here is the logic for CSR pipe read
+    // Compiler initializes ready register to 1, if ready register exist
+    // Non-Blocking uses_ready<true>
+    //   1. if ready == 1, fail.
+    //   2. Read data.
+    //   3. write 1 to ready.
+
+    // Blocking uses_ready<true>
+    //   1. wait until ready = 0.
+    //   2. read data.
+    //   3. write 1 to ready.
+
+    // uses_ready<false>
+    // Both Blocking and NonBlocking
+    //   1. Read data (always succeeds)
+
     unsigned long long parsed;
-    uintptr_t data_reg, ready_reg, valid_reg;
+    uintptr_t data_reg, ready_reg;
     // Convert the CSR address to a pointer
     try {
       parsed = std::stoull(host_pipe_info.csr_address, nullptr);
@@ -839,27 +854,21 @@ void acl_read_program_hostpipe(void *user_data, acl_device_op_t *op) {
     ready_reg = static_cast<uintptr_t>(
         parsed +
         csr_pipe_address_offet); // ready reg is data reg shift by 8 byte
-    valid_reg = static_cast<uintptr_t>(
-        parsed +
-        csr_pipe_address_offet * 2); // valid reg is ready reg shift by 8 byte
     unsigned ready = 1;
-    unsigned valid_value;
-    unsigned *valid_value_pointer = &valid_value;
+    unsigned ready_value;
+    unsigned *ready_value_pointer = &ready_value;
 
-    // protocol 3 is the avalon_mm_uses_ready protocol
-    // Only this uses_ready protocol requires reading/writing to ready&valid
-    // signals
-    if (host_pipe_info.protocol == 3) {
-      // If Blocking, wait until the data is valid.
-      // If Non-blocking, just read once and report failure if not valid.
+    if (host_pipe_info.is_stall_free == 0) {
+      // If Blocking, wait until the ready register = 0
+      // If Non-blocking, just read once and report failure if ready == 1
       do {
-        acl_get_hal()->read_csr(host_pipe_info.m_physical_device_id, valid_reg,
-                                (void *)valid_value_pointer,
+        acl_get_hal()->read_csr(host_pipe_info.m_physical_device_id, ready_reg,
+                                (void *)ready_value_pointer,
                                 (size_t)sizeof(uintptr_t));
-      } while (blocking && valid_value != 1);
+      } while (blocking && ready_value != 0);
 
-      // If non-blocking and valid bit is not set, set the op to fail.
-      if (!blocking && valid_value == 0) {
+      // If non-blocking and ready bit is 1, set the op to fail.
+      if (!blocking && ready_value == 1) {
         acl_mutex_unlock(&(host_pipe_info.m_lock));
         acl_set_device_op_execution_status(op, -1);
         return;
@@ -875,9 +884,8 @@ void acl_read_program_hostpipe(void *user_data, acl_device_op_t *op) {
       acl_set_device_op_execution_status(op, -1);
       return;
     }
-    // Tell CSR it's ready
-    // Same reason as above, only avalon_mm_uses_ready needs to do this.
-    if (host_pipe_info.protocol == 3) {
+    // Tell CSR it's ready if ready register exist
+    if (host_pipe_info.is_stall_free == 0) {
       acl_get_hal()->write_csr(host_pipe_info.m_physical_device_id, ready_reg,
                                (void *)&ready, (size_t)sizeof(uintptr_t));
     }
@@ -968,10 +976,19 @@ void acl_write_program_hostpipe(void *user_data, acl_device_op_t *op) {
     // Get CSR address
 
     // Here is the logic for CSR pipe write
-    // 1. If blocking, read valid reg, wait until valid is 0.
-    // 2. If non-blocking, read valid reg once ->return failure if valid is 1.
-    // 3. write to the pipe.
-    // 4. write 1 to the valid.
+    // Blocking uses_valid<true>:
+    //   1. read valid reg, wait until valid is 0
+    //   2. write to the pipe.
+    //   3. write 1 to the valid.
+
+    // Non-blocking uses_valid<true>
+    //   1. read valid reg once ->return failure if valid is 1
+    //   2. write to the pipe.
+    //   3. write 1 to the valid.
+
+    // uses_valid<false>
+    // Both Blocking and NonBlocking
+    //   1. Write data (always succeeds)
 
     unsigned long long parsed;
     uintptr_t data_reg, valid_reg;
@@ -990,23 +1007,24 @@ void acl_write_program_hostpipe(void *user_data, acl_device_op_t *op) {
     unsigned valid_value = 1;
     unsigned *valid_value_pointer = &valid_value;
 
-    if (blocking) {
-      // Wait until the valid reg is 0, before the write.
-      while (valid_value != 0) {
+    if (host_pipe_info.is_stall_free == 0) {
+      if (blocking) {
+        while (valid_value != 0) {
+          acl_get_hal()->read_csr(host_pipe_info.m_physical_device_id,
+                                  valid_reg, (void *)valid_value_pointer,
+                                  (size_t)sizeof(uintptr_t));
+        }
+      } else {
+        // Non-blocking, if valid reg is 1, return failure.
         acl_get_hal()->read_csr(host_pipe_info.m_physical_device_id, valid_reg,
                                 (void *)valid_value_pointer,
                                 (size_t)sizeof(uintptr_t));
-      }
-    } else {
-      // Non-blocking, if valid reg is 1, return failure.
-      acl_get_hal()->read_csr(host_pipe_info.m_physical_device_id, valid_reg,
-                              (void *)valid_value_pointer,
-                              (size_t)sizeof(uintptr_t));
 
-      if (valid_value == 1) {
-        acl_mutex_unlock(&(host_pipe_info.m_lock));
-        acl_set_device_op_execution_status(op, -1);
-        return;
+        if (valid_value == 1) {
+          acl_mutex_unlock(&(host_pipe_info.m_lock));
+          acl_set_device_op_execution_status(op, -1);
+          return;
+        }
       }
     }
 
@@ -1015,19 +1033,18 @@ void acl_write_program_hostpipe(void *user_data, acl_device_op_t *op) {
         host_pipe_info.m_physical_device_id, data_reg,
         event->cmd.info.host_pipe_dynamic_info.write_ptr,
         event->cmd.info.host_pipe_dynamic_info.size);
+
     if (status != 0) {
       acl_mutex_unlock(&(host_pipe_info.m_lock));
       acl_set_device_op_execution_status(op, -1);
       return;
     }
 
-    // For now, we trust the AVALON_MM by default uses valid.
-    // TODO: fix this later by using the new protocol info
-    // provided by the compiler.
-
-    const unsigned valid = 1;
-    acl_get_hal()->write_csr(host_pipe_info.m_physical_device_id, valid_reg,
-                             (void *)&valid, (size_t)sizeof(uintptr_t));
+    if (host_pipe_info.is_stall_free == 0) {
+      const unsigned valid = 1;
+      acl_get_hal()->write_csr(host_pipe_info.m_physical_device_id, valid_reg,
+                               (void *)&valid, (size_t)sizeof(uintptr_t));
+    }
 
   } else {
     // Regular hostpipe

src/acl_program.cpp

@@ -1364,6 +1364,7 @@ l_register_hostpipes_to_program(acl_device_program_info_t *dev_prog,
       }
     }
     host_pipe_info.protocol = hostpipe.protocol;
+    host_pipe_info.is_stall_free = hostpipe.is_stall_free;
     acl_mutex_init(&(host_pipe_info.m_lock), NULL);
     // The following property is not used by the program scoped hostpipe but we
     // don't want to leave it uninitialized

test/acl_auto_configure_test.cpp

@@ -1496,14 +1496,14 @@ TEST(auto_configure, cra_ring_root_exist) {
 
 TEST(auto_configure, hostpipe_mappings) {
   const std::string config_str{
-      "23 71 " RANDOM_HASH
+      "23 76 " RANDOM_HASH
       " pac_a10 0 1 13 DDR 2 2 24 1 2 0 4294967296 4294967296 8589934592 0 - 0 "
-      "0 0 0 0 0 1 5 9 " // 5 Hostpipes, 9 in each mapping
-      "pipe_logical_name1 pipe_physical_name1 1 12345 0 1 4 10 0 "
-      "pipe_logical_name2 pipe_physical_name2 0 12323 1 0 8 20 1 "
-      "pipe_logical_name3 pipe_physical_name1 1 12313 0 1 4 10 2 "
-      "pipe_logical_name5 pipe_physical_name1 0 12316 1 0 8 20 3 "
-      "pipe_logical_name4 pipe_physical_name3 0 12342 0 1 4 10 3 "
+      "0 0 0 0 0 1 5 10 " // 5 Hostpipes, 10 in each mapping
+      "pipe_logical_name1 pipe_physical_name1 1 12345 0 1 4 10 0 0 "
+      "pipe_logical_name2 pipe_physical_name2 0 12323 1 0 8 20 1 1 "
+      "pipe_logical_name3 pipe_physical_name1 1 12313 0 1 4 10 2 0 "
+      "pipe_logical_name5 pipe_physical_name1 0 12316 1 0 8 20 3 1 "
+      "pipe_logical_name4 pipe_physical_name3 0 12342 0 1 4 10 3 0 "
       "3 90 "
       "_ZTS3CRCILi0EE 512 256 1 0 0 1 0 1 0 9 6 0 0 8 1 0 0 6 2 1 8 1024 0 3 6 "
       "0 0 8 1 0 0 6 0 0 8 1 0 0 6 0 0 8 1 0 0 6 2 1 8 1024 0 2 6 0 0 8 1 0 0 "
@@ -1538,6 +1538,7 @@ TEST(auto_configure, hostpipe_mappings) {
   CHECK(devdef.hostpipe_mappings[0].pipe_width == 4);
   CHECK(devdef.hostpipe_mappings[0].pipe_depth == 10);
   CHECK(devdef.hostpipe_mappings[0].protocol == 0);
+  CHECK(devdef.hostpipe_mappings[0].is_stall_free == 0);
 
   CHECK(devdef.hostpipe_mappings[1].logical_name == "pipe_logical_name2");
   CHECK(devdef.hostpipe_mappings[1].physical_name == "pipe_physical_name2");
@@ -1548,6 +1549,7 @@ TEST(auto_configure, hostpipe_mappings) {
   CHECK(devdef.hostpipe_mappings[1].pipe_width == 8);
   CHECK(devdef.hostpipe_mappings[1].pipe_depth == 20);
   CHECK(devdef.hostpipe_mappings[1].protocol == 1);
+  CHECK(devdef.hostpipe_mappings[1].is_stall_free == 1);
 
   CHECK(devdef.hostpipe_mappings[2].logical_name == "pipe_logical_name3");
   CHECK(devdef.hostpipe_mappings[2].physical_name == "pipe_physical_name1");
@@ -1558,6 +1560,7 @@ TEST(auto_configure, hostpipe_mappings) {
   CHECK(devdef.hostpipe_mappings[2].pipe_width == 4);
   CHECK(devdef.hostpipe_mappings[2].pipe_depth == 10);
   CHECK(devdef.hostpipe_mappings[2].protocol == 2);
+  CHECK(devdef.hostpipe_mappings[2].is_stall_free == 0);
 
   CHECK(devdef.hostpipe_mappings[3].logical_name == "pipe_logical_name5");
   CHECK(devdef.hostpipe_mappings[3].physical_name == "pipe_physical_name1");
@@ -1568,6 +1571,7 @@ TEST(auto_configure, hostpipe_mappings) {
   CHECK(devdef.hostpipe_mappings[3].pipe_width == 8);
   CHECK(devdef.hostpipe_mappings[3].pipe_depth == 20);
   CHECK(devdef.hostpipe_mappings[3].protocol == 3);
+  CHECK(devdef.hostpipe_mappings[3].is_stall_free == 1);
 
   CHECK(devdef.hostpipe_mappings[4].logical_name == "pipe_logical_name4");
   CHECK(devdef.hostpipe_mappings[4].physical_name == "pipe_physical_name3");
@@ -1578,18 +1582,19 @@ TEST(auto_configure, hostpipe_mappings) {
   CHECK(devdef.hostpipe_mappings[4].pipe_width == 4);
   CHECK(devdef.hostpipe_mappings[4].pipe_depth == 10);
   CHECK(devdef.hostpipe_mappings[4].protocol == 3);
+  CHECK(devdef.hostpipe_mappings[4].is_stall_free == 0);
 }
 
 TEST(auto_configure, sideband_mappings) {
   const std::string config_str{
-      "23 102 " RANDOM_HASH
+      "23 107 " RANDOM_HASH
       " pac_a10 0 1 13 DDR 2 2 24 1 2 0 4294967296 4294967296 8589934592 0 - 0 "
-      "0 0 0 0 0 1 5 9 " // 5 Hostpipes, 9 in each mapping
-      "pipe_logical_name1 pipe_physical_name1 1 12345 0 1 4 10 0 "
-      "pipe_logical_name2 pipe_physical_name2 0 12323 1 0 8 20 1 "
-      "pipe_logical_name3 pipe_physical_name1 1 12313 0 1 4 10 2 "
-      "pipe_logical_name5 pipe_physical_name1 0 12316 1 0 8 20 3 "
-      "pipe_logical_name4 pipe_physical_name3 0 12342 0 1 4 10 3 "
+      "0 0 0 0 0 1 5 10 " // 5 Hostpipes, 10 in each mapping
+      "pipe_logical_name1 pipe_physical_name1 1 12345 0 1 4 10 0 0 "
+      "pipe_logical_name2 pipe_physical_name2 0 12323 1 0 8 20 1 1 "
+      "pipe_logical_name3 pipe_physical_name1 1 12313 0 1 4 10 2 0 "
+      "pipe_logical_name5 pipe_physical_name1 0 12316 1 0 8 20 3 1 "
+      "pipe_logical_name4 pipe_physical_name3 0 12342 0 1 4 10 3 0 "
       "2 " // 2 Sideband groups
       "pipe_logical_name1 4 3 0 0 320 1 320 8 2 328 8 3 352 32 "
       "pipe_logical_name2 4 3 0 0 320 1 320 8 2 328 8 3 352 32 "