This is a note to let you know that I've just added the patch titled
can: mcp251x: avoid repeated frame bug
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
can-mcp251x-avoid-repeated-frame-bug.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From cab32f39dcc5b35db96497dc0a026b5dea76e4e7 Mon Sep 17 00:00:00 2001
From: Benoît Locher <[email protected]>
Date: Mon, 27 Aug 2012 15:02:45 +0200
Subject: can: mcp251x: avoid repeated frame bug
From: Benoît Locher <[email protected]>
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 <[email protected]>
Signed-off-by: Marc Kleine-Budde <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/can/mcp251x.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- 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 s
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_dev
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,
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/can-mcp251x-avoid-repeated-frame-bug.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
