Re: [PATCH v3 3/3] hw/ssi/pnv_spi: Use local var seq_index instead of get_seq_index().

[Chalapathi V]

On 08-10-2024 13:43, Nicholas Piggin wrote:
On Thu Sep 19, 2024 at 2:50 AM AEST, Chalapathi V wrote:
Use a local variable seq_index instead of repeatedly caling
get_seq_index() method.

Signed-off-by: Chalapathi V <chalapath...@linux.ibm.com>
---
  hw/ssi/pnv_spi.c | 61 ++++++++++++++++++++++++------------------------
  1 file changed, 31 insertions(+), 30 deletions(-)

diff --git a/hw/ssi/pnv_spi.c b/hw/ssi/pnv_spi.c
index 2fd5aa0a96..962115f40f 100644
--- a/hw/ssi/pnv_spi.c
+++ b/hw/ssi/pnv_spi.c
@@ -210,15 +210,8 @@ static void transfer(PnvSpi *s)
      fifo8_reset(&s->rx_fifo);
  }
  
-static inline uint8_t get_seq_index(PnvSpi *s)
-{
-    return GETFIELD(SPI_STS_SEQ_INDEX, s->status);
-}
-
  static inline void next_sequencer_fsm(PnvSpi *s)
  {
-    uint8_t seq_index = get_seq_index(s);
-    s->status = SETFIELD(SPI_STS_SEQ_INDEX, s->status, (seq_index + 1));
      s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status, 
SEQ_STATE_INDEX_INCREMENT);
  }
  
@@ -647,6 +640,7 @@ static void operation_sequencer(PnvSpi *s)
      bool stop = false; /* Flag to stop the sequencer */
      uint8_t opcode = 0;
      uint8_t masked_opcode = 0;
+    uint8_t seq_index;
  
      /*
       * Clear the sequencer FSM error bit - general_SPI_status[3]
@@ -660,12 +654,13 @@ static void operation_sequencer(PnvSpi *s)
      if (GETFIELD(SPI_STS_SEQ_FSM, s->status) == SEQ_STATE_IDLE) {
          s->status = SETFIELD(SPI_STS_SEQ_INDEX, s->status, 0);
      }
+    seq_index = GETFIELD(SPI_STS_SEQ_INDEX, s->status);
      /*
       * There are only 8 possible operation IDs to iterate through though
       * some operations may cause more than one frame to be sequenced.
       */
-    while (get_seq_index(s) < NUM_SEQ_OPS) {
-        opcode = s->seq_op[get_seq_index(s)];
+    while (seq_index < NUM_SEQ_OPS) {
+        opcode = s->seq_op[seq_index];
          /* Set sequencer state to decode */
          s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status, SEQ_STATE_DECODE);
          /*
@@ -682,7 +677,7 @@ static void operation_sequencer(PnvSpi *s)
          case SEQ_OP_STOP:
              s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status, 
SEQ_STATE_EXECUTE);
              /* A stop operation in any position stops the sequencer */
-            trace_pnv_spi_sequencer_op("STOP", get_seq_index(s));
+            trace_pnv_spi_sequencer_op("STOP", seq_index);
  
              stop = true;
              s->status = SETFIELD(SPI_STS_SHIFTER_FSM, s->status, FSM_IDLE);
@@ -693,7 +688,7 @@ static void operation_sequencer(PnvSpi *s)
  
          case SEQ_OP_SELECT_SLAVE:
              s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status, 
SEQ_STATE_EXECUTE);
-            trace_pnv_spi_sequencer_op("SELECT_SLAVE", get_seq_index(s));
+            trace_pnv_spi_sequencer_op("SELECT_SLAVE", seq_index);
              /*
               * This device currently only supports a single responder
               * connection at position 0.  De-selecting a responder is fine
@@ -704,8 +699,7 @@ static void operation_sequencer(PnvSpi *s)
              if (s->responder_select == 0) {
                  trace_pnv_spi_shifter_done();
                  qemu_set_irq(s->cs_line[0], 1);
-                s->status = SETFIELD(SPI_STS_SEQ_INDEX, s->status,
-                                (get_seq_index(s) + 1));
+                seq_index++;
                  s->status = SETFIELD(SPI_STS_SHIFTER_FSM, s->status, 
FSM_DONE);
              } else if (s->responder_select != 1) {
                  qemu_log_mask(LOG_GUEST_ERROR, "Slave selection other than 1 "
@@ -732,13 +726,14 @@ static void operation_sequencer(PnvSpi *s)
                   * applies once a valid responder select has occurred.
                   */
                  s->shift_n1_done = false;
+                seq_index++;
                  next_sequencer_fsm(s);
Maybe could just open-code next_sequencer_fsm() now, since a bunch of
other FSM fields seem to be open-coded?
Sure.

              }
              break;
  
          case SEQ_OP_SHIFT_N1:
              s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status, 
SEQ_STATE_EXECUTE);
-            trace_pnv_spi_sequencer_op("SHIFT_N1", get_seq_index(s));
+            trace_pnv_spi_sequencer_op("SHIFT_N1", seq_index);
              /*
               * Only allow a shift_n1 when the state is not IDLE or DONE.
               * In either of those two cases the sequencer is not in a proper
@@ -770,8 +765,9 @@ static void operation_sequencer(PnvSpi *s)
                   * transmission to the responder without requiring a refill of
                   * the TDR between the two operations.
                   */
-                if (PNV_SPI_MASKED_OPCODE(s->seq_op[get_seq_index(s) + 1])
-                                == SEQ_OP_SHIFT_N2) {
+                if ((seq_index != 7) &&
+                    PNV_SPI_MASKED_OPCODE(s->seq_op[(seq_index + 1)]) ==
+                    SEQ_OP_SHIFT_N2) {
                      send_n1_alone = false;
                  }
                  s->status = SETFIELD(SPI_STS_SHIFTER_FSM, s->status,
The seq_index != 7 is a new test? Is that a separate fix, I'm not
seeing how it's related to the seq_index change.
Not a new test but to make sure array index of seq_op doesn't overflow 
due to seq_index + 1.

Thanks,
Nick