Allocate sufficient buffers for 1x1 config

xran's xran_bm_init() uses rte_pktmbuf_pool_create() to allocate DPDK
buffers. For a 1x1 configuration, the number of buffers might be too
small, and rte_pktmbuf_pool_create() might fail. This commit ensures
that we increase the number of buffers to have enough even in a 1x1
configuration. This works by chosing the next power of two, which is
recommended as per DPDK documentation.

Closes-Bug: #750

radio/fhi_72/oran-init.c

@@ -123,6 +123,14 @@ static struct xran_prb_map get_xran_prb_map_ul(const struct xran_fh_config *f)
   return prbmap;
 }
 
+static uint32_t next_power_2(uint32_t num)
+{
+  uint32_t power = 2;
+  while (power < num)
+    power <<= 1;
+  return power;
+}
+
 static uint32_t oran_allocate_uplane_buffers(
     void *instHandle,
     struct xran_buffer_list list[XRAN_MAX_ANTENNA_NR][XRAN_N_FE_BUF_LEN],
@@ -132,7 +140,10 @@ static uint32_t oran_allocate_uplane_buffers(
 {
   xran_status_t status;
   uint32_t pool;
-  uint32_t numBufs = XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT;
+  // we need at least XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT
+  // buffers, but xran_bm_init() uses rte_pktmbuf_pool_create() which
+  // recommends to use a power of two for the buffers
+  uint32_t numBufs = next_power_2(XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT);
   status = xran_bm_init(instHandle, &pool, numBufs, bufSize);
   AssertFatal(XRAN_STATUS_SUCCESS == status, "Failed at xran_bm_init(), status %d\n", status);
   printf("xran_bm_init() hInstance %p poolIdx %u elements %u size %u\n", instHandle, pool, numBufs, bufSize);
@@ -211,14 +222,14 @@ static void oran_allocate_cplane_buffers(void *instHandle,
 {
   xran_status_t status;
   uint32_t poolSec;
-  uint32_t numBufsSec = XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT * sect * XRAN_MAX_FRAGMENT;
+  uint32_t numBufsSec = next_power_2(XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT * sect * XRAN_MAX_FRAGMENT);
   uint32_t bufSizeSec = sizeof(struct xran_section_desc);
   status = xran_bm_init(instHandle, &poolSec, numBufsSec, bufSizeSec);
   AssertFatal(XRAN_STATUS_SUCCESS == status, "Failed at xran_bm_init(), status %d\n", status);
   printf("xran_bm_init() hInstance %p poolIdx %u elements %u size %u\n", instHandle, poolSec, numBufsSec, bufSizeSec);
 
   uint32_t poolPrb;
-  uint32_t numBufsPrb = XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT;
+  uint32_t numBufsPrb = next_power_2(XRAN_N_FE_BUF_LEN * ant * XRAN_NUM_OF_SYMBOL_PER_SLOT);
   uint32_t bufSizePrb = size_of_prb_map;
   status = xran_bm_init(instHandle, &poolPrb, numBufsPrb, bufSizePrb);
   AssertFatal(XRAN_STATUS_SUCCESS == status, "Failed at xran_bm_init(), status %d\n", status);