ipc: icbmsg: Reduce block alignment to 32-bits

The ICBMsg backend divides its memory into
blocks. Each block is aligned to data cache
alignment. Is it not required, since adjacent
blocks has the same data flow direction (either
read-only or write-only). This commit changes
it to 32-bits making wasted memory significantly
reduced.

Signed-off-by: Dominik Kilian <[email protected]>

subsys/ipc/ipc_service/backends/ipc_icbmsg.c

@@ -1295,6 +1295,11 @@ const static struct ipc_service_backend backend_ops = {
 	.release_rx_buffer = release_rx_buffer,
 };
 
+/**
+ * Required block alignment.
+ */
+#define BLOCK_ALIGNMENT sizeof(uint32_t)
+
 /**
  * Number of bytes per each ICMsg message. It is used to calculate size of ICMsg area.
  */
@@ -1308,28 +1313,28 @@ const static struct ipc_service_backend backend_ops = {
 	(PBUF_HEADER_OVERHEAD(GET_CACHE_ALIGNMENT(i)) + 2 * BYTES_PER_ICMSG_MESSAGE)
 
 /**
- * Returns required block alignment for instance "i".
+ * Returns required data cache alignment for instance "i".
  */
 #define GET_CACHE_ALIGNMENT(i) \
-	MAX(sizeof(uint32_t), DT_INST_PROP_OR(i, dcache_alignment, 0))
+	MAX(BLOCK_ALIGNMENT, DT_INST_PROP_OR(i, dcache_alignment, 0))
 
 /**
  * Calculates minimum size required for ICMsg region for specific number of local
  * and remote blocks. The minimum size ensures that ICMsg queue is will never overflow
  * because it can hold data message for each local block and release message
  * for each remote block.
  */
-#define GET_ICMSG_MIN_SIZE(i, local_blocks, remote_blocks)				\
+#define GET_ICMSG_MIN_SIZE(i, local_blocks, remote_blocks) ROUND_UP(			\
 	(ICMSG_BUFFER_OVERHEAD(i) + BYTES_PER_ICMSG_MESSAGE *				\
-	 (local_blocks + remote_blocks))
+	 (local_blocks + remote_blocks)), GET_CACHE_ALIGNMENT(i))
 
 /**
  * Calculate aligned block size by evenly dividing remaining space after removing
  * the space for ICMsg.
  */
 #define GET_BLOCK_SIZE(i, total_size, local_blocks, remote_blocks) ROUND_DOWN(		\
 	((total_size) - GET_ICMSG_MIN_SIZE(i, (local_blocks), (remote_blocks))) /	\
-	(local_blocks), GET_CACHE_ALIGNMENT(i))
+	(local_blocks), BLOCK_ALIGNMENT)
 
 /**
  * Calculate offset where area for blocks starts which is just after the ICMsg.
@@ -1434,11 +1439,11 @@ const static struct ipc_service_backend backend_ops = {
 	};										\
 	BUILD_ASSERT(IS_POWER_OF_TWO(GET_CACHE_ALIGNMENT(i)),				\
 		     "This module supports only power of two cache alignment");		\
-	BUILD_ASSERT((GET_BLOCK_SIZE_INST(i, tx, rx) >= GET_CACHE_ALIGNMENT(i)) &&	\
+	BUILD_ASSERT((GET_BLOCK_SIZE_INST(i, tx, rx) >= BLOCK_ALIGNMENT) &&		\
 		     (GET_BLOCK_SIZE_INST(i, tx, rx) <					\
 		      GET_MEM_SIZE_INST(i, tx)),					\
 		     "TX region is too small for provided number of blocks");		\
-	BUILD_ASSERT((GET_BLOCK_SIZE_INST(i, rx, tx) >= GET_CACHE_ALIGNMENT(i)) &&	\
+	BUILD_ASSERT((GET_BLOCK_SIZE_INST(i, rx, tx) >= BLOCK_ALIGNMENT) &&		\
 		     (GET_BLOCK_SIZE_INST(i, rx, tx) <					\
 		      GET_MEM_SIZE_INST(i, rx)),					\
 		     "RX region is too small for provided number of blocks");		\