diff options
Diffstat (limited to 'drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c')
| -rw-r--r-- | drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c index d3ac865933fd..e94321849fd7 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c @@ -21,6 +21,11 @@ static inline bool mcp251xfd_tx_fifo_sta_empty(u32 fifo_sta) return fifo_sta & MCP251XFD_REG_FIFOSTA_TFERFFIF; } +static inline bool mcp251xfd_tx_fifo_sta_less_than_half_full(u32 fifo_sta) +{ + return fifo_sta & MCP251XFD_REG_FIFOSTA_TFHRFHIF; +} + static inline int mcp251xfd_tef_tail_get_from_chip(const struct mcp251xfd_priv *priv, u8 *tef_tail) @@ -147,7 +152,29 @@ mcp251xfd_get_tef_len(struct mcp251xfd_priv *priv, u8 *len_p) BUILD_BUG_ON(sizeof(tx_ring->obj_num) != sizeof(len)); len = (chip_tx_tail << shift) - (tail << shift); - *len_p = len >> shift; + len >>= shift; + + /* According to mcp2518fd erratum DS80000789E 6. the FIFOCI + * bits of a FIFOSTA register, here the TX-FIFO tail index + * might be corrupted. + * + * However here it seems the bit indicating that the TX-FIFO + * is empty (MCP251XFD_REG_FIFOSTA_TFERFFIF) is not correct + * while the TX-FIFO tail index is. + * + * We assume the TX-FIFO is empty, i.e. all pending CAN frames + * haven been send, if: + * - Chip's head and tail index are equal (len == 0). + * - The TX-FIFO is less than half full. + * (The TX-FIFO empty case has already been checked at the + * beginning of this function.) + * - No free buffers in the TX ring. + */ + if (len == 0 && mcp251xfd_tx_fifo_sta_less_than_half_full(fifo_sta) && + mcp251xfd_get_tx_free(tx_ring) == 0) + len = tx_ring->obj_num; + + *len_p = len; return 0; } |