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

["Nicholas Piggin" <npiggin@gmail.com>]

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 <chalapathi.v@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?

>              }
>              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.

Thanks,
Nick