diff options
| author | Benoît Locher <Benoit.Locher@skf.com> | 2012-08-27 15:02:45 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-19 15:05:05 +0100 |
| commit | 0112e26a6a0f374041033fb5472f01db2658ac51 (patch) | |
| tree | 38c231866b9a50aacf5842dd098a8b5e339f8f04 /drivers | |
| parent | f094377d3dc8bbf4baf9db85f88cd65fb1fccd1a (diff) | |
can: mcp251x: avoid repeated frame bug
commit cab32f39dcc5b35db96497dc0a026b5dea76e4e7 upstream.
The MCP2515 has a silicon bug causing repeated frame transmission, see section
5 of MCP2515 Rev. B Silicon Errata Revision G (March 2007).
Basically, setting TXBnCTRL.TXREQ in either SPI mode (00 or 11) will eventually
cause the bug. The workaround proposed by Microchip is to use mode 00 and send
a RTS command on the SPI bus to initiate the transmission.
Signed-off-by: Benoît Locher <Benoit.Locher@skf.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/can/mcp251x.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c index 330140ee266..9bcc39a07c4 100644 --- a/drivers/net/can/mcp251x.c +++ b/drivers/net/can/mcp251x.c @@ -83,6 +83,11 @@ #define INSTRUCTION_LOAD_TXB(n) (0x40 + 2 * (n)) #define INSTRUCTION_READ_RXB(n) (((n) == 0) ? 0x90 : 0x94) #define INSTRUCTION_RESET 0xC0 +#define RTS_TXB0 0x01 +#define RTS_TXB1 0x02 +#define RTS_TXB2 0x04 +#define INSTRUCTION_RTS(n) (0x80 | ((n) & 0x07)) + /* MPC251x registers */ #define CANSTAT 0x0e @@ -397,6 +402,7 @@ static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf, static void mcp251x_hw_tx(struct spi_device *spi, struct can_frame *frame, int tx_buf_idx) { + struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev); u32 sid, eid, exide, rtr; u8 buf[SPI_TRANSFER_BUF_LEN]; @@ -418,7 +424,10 @@ static void mcp251x_hw_tx(struct spi_device *spi, struct can_frame *frame, buf[TXBDLC_OFF] = (rtr << DLC_RTR_SHIFT) | frame->can_dlc; memcpy(buf + TXBDAT_OFF, frame->data, frame->can_dlc); mcp251x_hw_tx_frame(spi, buf, frame->can_dlc, tx_buf_idx); - mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx), TXBCTRL_TXREQ); + + /* use INSTRUCTION_RTS, to avoid "repeated frame problem" */ + priv->spi_tx_buf[0] = INSTRUCTION_RTS(1 << tx_buf_idx); + mcp251x_spi_trans(priv->spi, 1); } static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf, |