Merge remote-tracking branch 'origin/prach-fft' into integration_2025_w52 (!3809)

[FHI72] Fix the PRACH FFT size

ru_config->fftSize is used for the C-plane Section Type 3 which is
dedicated for PRACH and mixed numerology. Previously, we assumed that
PRACH FFT size is equivalent to PxSCH FFT size, but should be based on
the PRACH format.

Tests with the following RUs:

- [x] Benetel v1.2.2 & v1.4.1
- [x] VVDN Gen 3
- [x] Liteon 02.00.10
- [x] Metanoia v2.2.8 (Jura)

executables/nr-ru.c

@@ -896,6 +896,7 @@ static void fill_split7_2_config(split7_config_t *split7, const nfapi_nr_config_
     }
   }
 
+  split7->prach_fftSize = prach_config->prach_sequence_length.value == 0 ? 10 : 8; // need to handle 5kHz cases better than this
   split7->fftSize = log2(fp->ofdm_symbol_size);
 
   // M-plane related parameters

radio/COMMON/common_lib.h

@@ -199,6 +199,8 @@ typedef struct split7_config {
   /*! this is the exponent in 2^X for the FFT size */
   uint16_t fftSize;
 
+  /*! this is the ceil of the exponent in 2^X for the prach FFT size */
+  uint16_t prach_fftSize;
   // M-plane related parameters
   uint16_t dl_k0[5];
   uint16_t ul_k0[5];

radio/fhi_72/oaioran.c

@@ -338,7 +338,7 @@ int xran_fh_rx_read_slot(ru_info_t *ru, int *frame, int *slot)
 
   const struct xran_fh_init *fh_init = get_xran_fh_init();
   int nPRBs = fh_cfg->nULRBs;
-  int fftsize = 1 << fh_cfg->ru_conf.fftSize;
+  int fftsize = 1 << fh_cfg->nULFftSize;
 
   int slot_offset_rxdata = 3 & (*slot);
   uint32_t slot_size = 4 * 14 * fftsize;
@@ -496,7 +496,7 @@ int xran_fh_tx_send_slot(ru_info_t *ru, int frame, int slot, uint64_t timestamp)
   const struct xran_fh_init *fh_init = get_xran_fh_init();
   const struct xran_fh_config *fh_cfg = get_xran_fh_config(0);
   int nPRBs = fh_cfg->nDLRBs;
-  int fftsize = 1 << fh_cfg->ru_conf.fftSize;
+  int fftsize = 1 << fh_cfg->nDLFftSize;
   int nb_tx_per_ru = ru->nb_tx / fh_init->xran_ports;
   int nb_rx_per_ru = ru->nb_rx / fh_init->xran_ports;
 

radio/fhi_72/oran-config.c

@@ -921,8 +921,8 @@ static bool set_fh_config(void *mplane_api, int ru_idx, int num_rus, enum xran_c
   fh_config->neAxc = RTE_MAX(oai0->tx_num_channels / num_rus, oai0->rx_num_channels / num_rus); // number of eAxc supported on one CC = max(PDSCH, PUSCH)
   fh_config->neAxcUl = 0; // number of eAxc supported on one CC for UL direction = PUSCH; used only if XRAN_CATEGORY_B
   fh_config->nAntElmTRx = 0; // number of antenna elements for TX and RX = SRS; used only if XRAN_CATEGORY_B
-  fh_config->nDLFftSize = 0; // DL FFT size; not used in xran
-  fh_config->nULFftSize = 0; // UL FFT size; not used in xran
+  fh_config->nDLFftSize = oai0->split7.fftSize; // DL FFT size; not used in xran
+  fh_config->nULFftSize = oai0->split7.fftSize; // UL FFT size; not used in xran
   fh_config->nDLRBs = oai0->num_rb_dl; // DL PRB; used in oaioran.c/oran-init.c; not used in xran, neither in E nor in F release
   fh_config->nULRBs = oai0->num_rb_dl; // UL PRB; used in oaioran.c/oran-init.c; in xran E release not used so the patch fixes it, but in xran F release this value is properly used
   fh_config->nDLAbsFrePointA = 0; // Abs Freq Point A of the Carrier Center Frequency for in KHz Value; not used in xran
@@ -966,7 +966,7 @@ static bool set_fh_config(void *mplane_api, int ru_idx, int num_rus, enum xran_c
   // fh_config->srs_conf = {0};
   if (!set_fh_frame_config(oai0, &fh_config->frame_conf))
     return false;
-  if (!set_fh_ru_config(mplane_api, rup, oai0->split7.fftSize, nru, xran_cat, &fh_config->ru_conf))
+  if (!set_fh_ru_config(mplane_api, rup, oai0->split7.prach_fftSize, nru, xran_cat, &fh_config->ru_conf))
     return false;
 
   fh_config->bbdev_enc = NULL; // call back to poll BBDev encoder