From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Tue, 5 Jan 2021 21:41:38 +0000 (+0100)
Subject: can: mcp251xfd: mcp251xfd_handle_rxif_ring(): first increment RX tail pointer in... 
X-Git-Tag: accepted/tizen/unified/20230118.172025~8123^2~11^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2fbb397f584077e3c90abd06829f5a1f66fdd5f4;p=platform%2Fkernel%2Flinux-rpi.git

can: mcp251xfd: mcp251xfd_handle_rxif_ring(): first increment RX tail pointer in HW, then in driver

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 <mkl@pengutronix.de>
---

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 85a1a8b..36235af 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;