On 27.01.2023 13:42:58, Thomas Kopp wrote:
> For CRC transfers with size 1 it is more efficient to use the
> write_safe command instead of the write_crc command. This saves the
> length byte on the SPI transfer.
Looks good to me. But I cannot measure a difference.
> Signed-off-by: Thomas Kopp <thomas.kopp@xxxxxxxxxxxxx>
> ---
> .../net/can/spi/mcp251xfd/mcp251xfd-ring.c | 31 ++++++++++++-------
> drivers/net/can/spi/mcp251xfd/mcp251xfd.h | 26 +++++++++++++---
> 2 files changed, 42 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
> index f69d5fc8c9afd..3c3bc9be1f295 100644
> --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
> +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ring.c
> @@ -30,22 +30,31 @@ mcp251xfd_cmd_prepare_write_reg(const struct mcp251xfd_priv *priv,
> last_byte = mcp251xfd_last_byte_set(mask);
> len = last_byte - first_byte + 1;
>
> - data = mcp251xfd_spi_cmd_write(priv, write_reg_buf, reg + first_byte);
> + data = mcp251xfd_spi_cmd_write(priv, write_reg_buf, reg + first_byte, len);
> val_le32 = cpu_to_le32(val >> BITS_PER_BYTE * first_byte);
> memcpy(data, &val_le32, len);
>
> if (priv->devtype_data.quirks & MCP251XFD_QUIRK_CRC_REG) {
> u16 crc;
> -
> - mcp251xfd_spi_cmd_crc_set_len_in_reg(&write_reg_buf->crc.cmd,
> - len);
> - /* CRC */
> - len += sizeof(write_reg_buf->crc.cmd);
> - crc = mcp251xfd_crc16_compute(&write_reg_buf->crc, len);
> - put_unaligned_be16(crc, (void *)write_reg_buf + len);
> -
> - /* Total length */
> - len += sizeof(write_reg_buf->crc.crc);
> + if (len == 1) {
> + /* CRC */
> + len += sizeof(write_reg_buf->safe.cmd);
> + crc = mcp251xfd_crc16_compute(&write_reg_buf->safe, len);
> + put_unaligned_be16(crc, (void *)write_reg_buf + len);
> +
> + /* Total length */
> + len += sizeof(write_reg_buf->safe.crc);
> + } else {
> + mcp251xfd_spi_cmd_crc_set_len_in_reg(&write_reg_buf->crc.cmd,
> + len);
> + /* CRC */
> + len += sizeof(write_reg_buf->crc.cmd);
> + crc = mcp251xfd_crc16_compute(&write_reg_buf->crc, len);
> + put_unaligned_be16(crc, (void *)write_reg_buf + len);
> +
> + /* Total length */
> + len += sizeof(write_reg_buf->crc.crc);
> + }
> } else {
> len += sizeof(write_reg_buf->nocrc.cmd);
> }
I've moved changed the if() logic a bit, saving 1 level of indention.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
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