In Classical CAN there are RTR frames. RTR frames have the RTR bit set, may have a dlc != 0, but contain no data.
This patch optimizes the TX-path to not copy any data for RTR frames. Link: https://lore.kernel.org/r/20210114153448.1506901-5-...@pengutronix.de Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de> --- drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c index 92816be4f3d4..e6d98e172a47 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c @@ -2304,7 +2304,7 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv, union mcp251xfd_tx_obj_load_buf *load_buf; u8 dlc; u32 id, flags; - int pad_len, len; + int len_sanitized = 0, len; if (cfd->can_id & CAN_EFF_FLAG) { u32 sid, eid; @@ -2331,6 +2331,8 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv, if (cfd->can_id & CAN_RTR_FLAG) flags |= MCP251XFD_OBJ_FLAGS_RTR; + else + len_sanitized = canfd_sanitize_len(cfd->len); /* CANFD */ if (can_is_canfd_skb(skb)) { @@ -2356,14 +2358,18 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv, memcpy(hw_tx_obj->data, cfd->data, cfd->len); /* Clear unused data at end of CAN frame */ - pad_len = can_fd_dlc2len(dlc) - cfd->len; - if (MCP251XFD_SANITIZE_CAN && pad_len) - memset(hw_tx_obj->data + cfd->len, 0x0, pad_len); + if (MCP251XFD_SANITIZE_CAN && len_sanitized) { + int pad_len; + + pad_len = len_sanitized - cfd->len; + if (pad_len) + memset(hw_tx_obj->data + cfd->len, 0x0, pad_len); + } /* Number of bytes to be written into the RAM of the controller */ len = sizeof(hw_tx_obj->id) + sizeof(hw_tx_obj->flags); if (MCP251XFD_SANITIZE_CAN) - len += round_up(can_fd_dlc2len(dlc), sizeof(u32)); + len += round_up(len_sanitized, sizeof(u32)); else len += round_up(cfd->len, sizeof(u32)); -- 2.29.2
