CAN-FD frames have only specific frame length (0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 32, 48, 64). A CAN-FD frame provided by user space might not cover the whole CAN-FD frame. To avoid sending garbage over the CAN bus the driver pads the CAN frame with 0x0 (if MCP251XFD_SANITIZE_CAN is activated). This patch cleans up the pad len calculation. Rounding to full u32 brings no benefit, in case of CRC transfers, the hw_tx_obj->data is not aligned to u32 anyway. Link: https://lore.kernel.org/r/20210114153448.1506901-3-mkl@xxxxxxxxxxxxxx Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c index 1dbb87c28049..aa992e71d787 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c @@ -2303,7 +2303,7 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv, union mcp251xfd_tx_obj_load_buf *load_buf; u8 dlc; u32 id, flags; - int offset, len; + int pad_len, len; if (cfd->can_id & CAN_EFF_FLAG) { u32 sid, eid; @@ -2351,13 +2351,14 @@ mcp251xfd_tx_obj_from_skb(const struct mcp251xfd_priv *priv, put_unaligned_le32(id, &hw_tx_obj->id); put_unaligned_le32(flags, &hw_tx_obj->flags); - /* Clear data at end of CAN frame */ - offset = round_down(cfd->len, sizeof(u32)); - len = round_up(can_fd_dlc2len(dlc), sizeof(u32)) - offset; - if (MCP251XFD_SANITIZE_CAN && len) - memset(hw_tx_obj->data + offset, 0x0, len); + /* Copy data */ 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); + /* 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) -- 2.29.2
