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drivers: CAN: MCP2515: Optimise TX SPI data length

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When loading the TX buffer via SPI only transfer the data bytes of
the CAN message that will be used as defined by the DLC.

Signed-off-by: Nick Ward <nix.ward@gmail.com>
This commit is contained in:
Nick Ward 2019-10-24 22:15:17 +11:00 • committed by Ioannis Glaropoulos
commit ee99749ee5
1 changed files with 7 additions and 3 deletions
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10
drivers/can/can_mcp2515.c
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@ -216,7 +216,7 @@ static void mcp2515_convert_zcanframe_to_mcp2515frame(const struct zcan_frame
target[MCP2515_FRAME_OFFSET_DLC] = rtr | dlc;
for (; data_idx < 8; data_idx++) {
for (; data_idx < CAN_MAX_DLC; data_idx++) {
target[MCP2515_FRAME_OFFSET_D0 + data_idx] =
source->data[data_idx];
}
@ -245,7 +245,7 @@ static void mcp2515_convert_mcp2515frame_to_zcanframe(const u8_t *source,
target->rtr = source[MCP2515_FRAME_OFFSET_DLC] & BIT(6) ?
CAN_REMOTEREQUEST : CAN_DATAFRAME;
for (; data_idx < 8; data_idx++) {
for (; data_idx < CAN_MAX_DLC; data_idx++) {
target->data[data_idx] = source[MCP2515_FRAME_OFFSET_D0 +
data_idx];
}
@ -386,6 +386,7 @@ static int mcp2515_send(struct device *dev, const struct zcan_frame *msg,
u8_t tx_idx = 0U;
u8_t abc;
u8_t nnn;
u8_t len;
u8_t tx_frame[MCP2515_FRAME_LEN];
if (msg->dlc > CAN_MAX_DLC) {
@ -422,7 +423,10 @@ static int mcp2515_send(struct device *dev, const struct zcan_frame *msg,
/* Address Pointer selection */
abc = 2 * tx_idx;
mcp2515_cmd_load_tx_buffer(dev, abc, tx_frame, sizeof(tx_frame));
/* Calculate minimum length to transfer */
len = sizeof(tx_frame) - CAN_MAX_DLC + msg->dlc;
mcp2515_cmd_load_tx_buffer(dev, abc, tx_frame, len);
/* request tx slot transmission */
nnn = BIT(tx_idx);