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drivers: can: mcp2515: reduce the number of tx buffers to 1

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Reduce the number of TX buffers in use on the MCP2515 from 3 to 1 in
order to avoid CAN frame priority inversion.

The MCP2515 is unable to do internal TX frame arbitration based on the
CAN-ID of the frame. Priority must be set per TX buffer and the priority
cannot be rewritten unless the frame transmission is aborted.

Fixes: #26541

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
This commit is contained in:
Henrik Brix Andersen 2022-02-10 17:04:27 +01:00 committed by Anas Nashif
parent 2bd18c6cfd
commit 7815de13c3
2 changed files with 9 additions and 8 deletions
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14
drivers/can/can_mcp2515.c
View file

@ -839,15 +839,18 @@ static int mcp2515_init(const struct device *dev)
{
const struct mcp2515_config *dev_cfg = dev->config;
struct mcp2515_data *dev_data = dev->data;
int ret;
struct can_timing timing;
int ret;
int i;
k_sem_init(&dev_data->int_sem, 0, 1);
k_mutex_init(&dev_data->mutex);
k_sem_init(&dev_data->tx_sem, MCP2515_TX_CNT, MCP2515_TX_CNT);
k_sem_init(&dev_data->tx_cb[0].sem, 0, 1);
k_sem_init(&dev_data->tx_cb[1].sem, 0, 1);
k_sem_init(&dev_data->tx_cb[2].sem, 0, 1);
for (i = 0; i < MCP2515_TX_CNT; i++) {
k_sem_init(&dev_data->tx_cb[i].sem, 0, 1);
dev_data->tx_cb[i].cb = NULL;
}
if (!spi_is_ready(&dev_cfg->bus)) {
LOG_ERR("SPI bus %s not ready", dev_cfg->bus.bus->name);
@ -934,9 +937,6 @@ static K_KERNEL_STACK_DEFINE(mcp2515_int_thread_stack,
static struct mcp2515_data mcp2515_data_1 = {
.int_thread_stack = mcp2515_int_thread_stack,
.tx_cb[0].cb = NULL,
.tx_cb[1].cb = NULL,
.tx_cb[2].cb = NULL,
.tx_busy_map = 0U,
.filter_usage = 0U,
};

3
drivers/can/can_mcp2515.h
View file

@ -11,7 +11,8 @@
#include <drivers/can.h>
#define MCP2515_RX_CNT 2
#define MCP2515_TX_CNT 3
/* Reduce the number of Tx buffers to 1 in order to avoid priority inversion. */
#define MCP2515_TX_CNT 1
#define MCP2515_FRAME_LEN 13
struct mcp2515_tx_cb {