# \[net 4/6\] can: mcp251xfd: mcp251xfd\_handle\_rxif\_ring(): first increment RX tail pointer in HW, then in driver - From: Marc Kleine-Budde \ - Date: 2021-01-07 10:36:29 - List: netdev - Page: https://ratatoskr.run/netdev/2021/01/9354978 - Thread: https://ratatoskr.run/netdev/2021/01/9354972/t.md ```text The previous patch fixes a TEF vs. TX race condition, by first updating the TEF tail pointer in hardware, and then updating the driver internal pointer. The same pattern exists in the RX-path, too. This should be no problem, as the driver accesses the RX-FIFO from the interrupt handler only, thus the access is properly serialized. Fix the order here, too, so that the TEF- and RX-path look similar. Fixes: 1f652bb6bae7 ("can: mcp25xxfd: rx-path: reduce number of SPI core requests to set UINC bit") Link: https://lore.kernel.org/r/20210105214138.3150886-3-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde --- drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c index 85a1a8b7c0e7..36235afb0bc6 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c @@ -1552,10 +1552,8 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv, /* Increment the RX FIFO tail pointer 'len' times in a * single SPI message. - */ - ring->tail += len; - - /* Note: + * + * Note: * * "cs_change == 1" on the last transfer results in an * active chip select after the complete SPI @@ -1571,6 +1569,8 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv, last_xfer->cs_change = 1; if (err) return err; + + ring->tail += len; } return 0; -- 2.29.2 ```