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can: mcp251xfd: mcp251xfd_get_tef_len(): fix length calculation

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Commit b8e0ddd36c ("can: mcp251xfd: tef: prepare to workaround
broken TEF FIFO tail index erratum") introduced
mcp251xfd_get_tef_len() to get the number of unhandled transmit events
from the Transmit Event FIFO (TEF).

As the TEF has no head pointer, the driver uses the TX FIFO's tail
pointer instead, assuming that send frames are completed. However the
check for the TEF being full was not correct. This leads to the driver
stop working if the TEF is full.

Fix the TEF full check by assuming that if, from the driver's point of
view, there are no free TX buffers in the chip and the TX FIFO is
empty, all messages must have been sent and the TEF must therefore be
full.

Reported-by: Sven Schuchmann <schuchmann@schleissheimer.de>
Closes: https://patch.msgid.link/FR3P281MB155216711EFF900AD9791B7ED9692@FR3P281MB1552.DEUP281.PROD.OUTLOOK.COM
Fixes: b8e0ddd36c ("can: mcp251xfd: tef: prepare to workaround broken TEF FIFO tail index erratum")
Tested-by: Sven Schuchmann <schuchmann@schleissheimer.de>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20241104-mcp251xfd-fix-length-calculation-v3-1-608b6e7e2197@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Marc Kleine-Budde 2024-10-01 16:56:22 +02:00
parent eb9a839b3d
commit 3c1c18551e
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c
View File

@ -16,9 +16,9 @@
#include "mcp251xfd.h"
static inline bool mcp251xfd_tx_fifo_sta_full(u32 fifo_sta)
static inline bool mcp251xfd_tx_fifo_sta_empty(u32 fifo_sta)
{
return !(fifo_sta & MCP251XFD_REG_FIFOSTA_TFNRFNIF);
return fifo_sta & MCP251XFD_REG_FIFOSTA_TFERFFIF;
}
static inline int
@ -122,7 +122,11 @@ mcp251xfd_get_tef_len(struct mcp251xfd_priv *priv, u8 *len_p)
if (err)
return err;
if (mcp251xfd_tx_fifo_sta_full(fifo_sta)) {
/* If the chip says the TX-FIFO is empty, but there are no TX
* buffers free in the ring, we assume all have been sent.
*/
if (mcp251xfd_tx_fifo_sta_empty(fifo_sta) &&
mcp251xfd_get_tx_free(tx_ring) == 0) {
*len_p = tx_ring->obj_num;
return 0;
}