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    SubjectRe: [PATCH v2 05/15] spi: dw: Introduce enhanced mem_op
    On Mon, Dec 12, 2022 at 06:07:22PM +0000, Sudip Mukherjee wrote:
    > If the DW_SPI_CAP_EMODE capability is enabled then dw_spi_exec_enh_mem_op()
    > will be used as the new enhanced mem_op. Lets initialize the buffer and
    > get the pointers to receive and transmit data buffers.
    > The DW_SPI_CAP_EMODE capability will be enabled in a later patch.
    >
    > Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
    > ---
    > drivers/spi/spi-dw-core.c | 53 ++++++++++++++++++++++++++++++++++++---
    > 1 file changed, 50 insertions(+), 3 deletions(-)
    >
    > diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
    > index 49fad58ceb94a..89438ae2df17d 100644
    > --- a/drivers/spi/spi-dw-core.c
    > +++ b/drivers/spi/spi-dw-core.c
    > @@ -798,6 +798,51 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
    > return ret;
    > }
    >
    > +static void dw_spi_init_enh_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
    > +{
    > + unsigned int i, j;
    > + u8 *out;
    > +

    > + out = dws->buf;
    > + for (i = 0; i < DW_SPI_BUF_SIZE; ++i)
    > + out[i] = 0;
    > +
    > + for (i = 0, j = op->cmd.nbytes; i < op->cmd.nbytes; ++i, --j)
    > + out[i] = DW_SPI_GET_BYTE(op->cmd.opcode, op->cmd.nbytes - j);
    > +
    > + for (j = op->addr.nbytes, i = dws->reg_io_width; j > 0; ++i, --j)
    > + out[i] = DW_SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j);

    In case of the non-eSPI implementation the outbound data consolidation
    was required to get the most optimal loop of data transfer. In this
    case I don't see it was required since the clock stretching feature is
    available and the IRQ-based xfer procedure is implemented. Do I miss
    something?

    -Serge(y)

    > +
    > + dws->n_bytes = 1;
    > + if (op->data.dir == SPI_MEM_DATA_IN) {
    > + dws->rx = op->data.buf.in;
    > + dws->rx_len = op->data.nbytes;
    > + dws->tx = NULL;
    > + dws->tx_len = 0;
    > + } else if (op->data.dir == SPI_MEM_DATA_OUT) {
    > + dws->tx_len = op->data.nbytes;
    > + dws->tx = (void *)op->data.buf.out;
    > + dws->rx = NULL;
    > + dws->rx_len = 0;
    > + } else {
    > + dws->rx = NULL;
    > + dws->rx_len = 0;
    > + dws->tx = NULL;
    > + dws->tx_len = 0;
    > + }
    > +}
    > +
    > +static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
    > +{
    > + struct spi_controller *ctlr = mem->spi->controller;
    > + struct dw_spi *dws = spi_controller_get_devdata(ctlr);
    > +
    > + /* Collect cmd and addr into a single buffer */
    > + dw_spi_init_enh_mem_buf(dws, op);
    > +
    > + return 0;
    > +}
    > +
    > /*
    > * Initialize the default memory operations if a glue layer hasn't specified
    > * custom ones. Direct mapping operations will be preserved anyway since DW SPI
    > @@ -812,11 +857,13 @@ static void dw_spi_init_mem_ops(struct dw_spi *dws)
    > if (!dws->mem_ops.exec_op && !(dws->caps & DW_SPI_CAP_CS_OVERRIDE) &&
    > !dws->set_cs) {
    > dws->mem_ops.adjust_op_size = dw_spi_adjust_mem_op_size;
    > - if (dws->caps & DW_SPI_CAP_EMODE)
    > + if (dws->caps & DW_SPI_CAP_EMODE) {
    > + dws->mem_ops.exec_op = dw_spi_exec_enh_mem_op;
    > dws->mem_ops.supports_op = dw_spi_supports_enh_mem_op;
    > - else
    > + } else {
    > + dws->mem_ops.exec_op = dw_spi_exec_mem_op;
    > dws->mem_ops.supports_op = dw_spi_supports_mem_op;
    > - dws->mem_ops.exec_op = dw_spi_exec_mem_op;
    > + }
    > if (!dws->max_mem_freq)
    > dws->max_mem_freq = dws->max_freq;
    > }
    > --
    > 2.30.2
    >

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