pull-request: can 2021-01-07

Hello Jakub, hello David,

this is a pull request of 6 patches for net/master.

The first patch is by me for the m_can driver and removes an erroneous
m_can_clk_stop() from the driver's unregister function.

The second patch targets the tcan4x5x driver, is by me, and fixes the bit
timing constant parameters.

The next two patches are by me, target the mcp251xfd driver, and fix a race
condition in the optimized TEF path (which was added in net-next for v5.11).
The similar code in the RX path is changed to look the same, although it
doesn't suffer from the race condition.

A patch by Lad Prabhakar updates the description and help text for the rcar CAN
driver to reflect all supported SoCs.

In the last patch Sriram Dash transfers the maintainership of the m_can driver
to Pankaj Sharma.

regards,
Marc

---

The following changes since commit 1f685e6adbbe3c7b1bd9053be771b898d9efa655:

  ptp: ptp_ines: prevent build when HAS_IOMEM is not set (2021-01-06 16:17:23 -0800)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git tags/linux-can-fixes-for-5.11-20210107

for you to fetch changes up to 6ee49118f87cf02b36f68812bc49855b7b627a2b:

  MAINTAINERS: Update MCAN MMIO device driver maintainer (2021-01-07 11:02:10 +0100)

----------------------------------------------------------------
linux-can-fixes-for-5.11-20210107

----------------------------------------------------------------
Lad Prabhakar (1):
      can: rcar: Kconfig: update help description for CAN_RCAR config

Marc Kleine-Budde (4):
      can: m_can: m_can_class_unregister(): remove erroneous m_can_clk_stop()
      can: tcan4x5x: fix bittiming const, use common bittiming from m_can driver
      can: mcp251xfd: mcp251xfd_handle_tefif(): fix TEF vs. TX race condition
      can: mcp251xfd: mcp251xfd_handle_rxif_ring(): first increment RX tail pointer in HW, then in driver

Sriram Dash (1):
      MAINTAINERS: Update MCAN MMIO device driver maintainer

 MAINTAINERS                                    |  2 +-
 drivers/net/can/m_can/m_can.c                  |  2 --
 drivers/net/can/m_can/tcan4x5x.c               | 26 --------------------------
 drivers/net/can/rcar/Kconfig                   |  4 ++--
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 17 ++++++++---------
 5 files changed, 11 insertions(+), 40 deletions(-)

The mcp251xfd driver uses a TX FIFO for sending CAN frames and a TX Event FIFO
(TEF) for completed TX-requests.

The TEF event handling in the mcp251xfd_handle_tefif() function has a race
condition. It first increments the tx-ring's tail counter to signal that
there's room in the TX and TEF FIFO, then it increments the TEF FIFO in
hardware.

A running mcp251xfd_start_xmit() on a different CPU might not stop the txqueue
(as the tx-ring still shows free space). The next mcp251xfd_start_xmit() will
push a message into the chip and the TX complete event might overflow the TEF
FIFO.

This patch changes the order to fix the problem.

Fixes: 68c0c1c7f966 ("can: mcp251xfd: tef-path: reduce number of SPI core requests to set UINC bit")
Link: https://lore.kernel.org/r/20210105214138.3150886-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 77129d5f410b..85a1a8b7c0e7 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c

@@ -1368,13 +1368,10 @@ static int mcp251xfd_handle_tefif(struct mcp251xfd_priv *priv)
 		struct mcp251xfd_tx_ring *tx_ring = priv->tx;
 		struct spi_transfer *last_xfer;
 
-		tx_ring->tail += len;
-
 		/* Increment the TEF FIFO tail pointer 'len' times in
 		 * a single SPI message.
-		 */
-
-		/* Note:
+		 *
+		 * Note:
 		 *
 		 * "cs_change == 1" on the last transfer results in an
 		 * active chip select after the complete SPI

@@ -1391,6 +1388,8 @@ static int mcp251xfd_handle_tefif(struct mcp251xfd_priv *priv)
 		if (err)
 			return err;
 
+		tx_ring->tail += len;
+
 		err = mcp251xfd_check_tef_tail(priv);
 		if (err)
 			return err;

-- 
2.29.2

According to the TCAN4550 datasheet "SLLSF91 - DECEMBER 2018" the tcan4x5x has
the same bittiming constants as a m_can revision 3.2.x/3.3.0.

The tcan4x5x chip I'm using identifies itself as m_can revision 3.2.1, so
remove the tcan4x5x specific bittiming values and rely on the values in the
m_can driver, which are selected according to core revision.

Fixes: 5443c226ba91 ("can: tcan4x5x: Add tcan4x5x driver to the kernel")
Cc: Dan Murphy <redacted>
Reviewed-by: Sean Nyekjaer <redacted>
Link: https://lore.kernel.org/r/20201215103238.524029-3-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/tcan4x5x.c | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/net/can/m_can/tcan4x5x.c b/drivers/net/can/m_can/tcan4x5x.c
index 24c737c4fc44..970f0e9d19bf 100644
--- a/drivers/net/can/m_can/tcan4x5x.c
+++ b/drivers/net/can/m_can/tcan4x5x.c

@@ -131,30 +131,6 @@ static inline struct tcan4x5x_priv *cdev_to_priv(struct m_can_classdev *cdev)
 
 }
 
-static struct can_bittiming_const tcan4x5x_bittiming_const = {
-	.name = DEVICE_NAME,
-	.tseg1_min = 2,
-	.tseg1_max = 31,
-	.tseg2_min = 2,
-	.tseg2_max = 16,
-	.sjw_max = 16,
-	.brp_min = 1,
-	.brp_max = 32,
-	.brp_inc = 1,
-};
-
-static struct can_bittiming_const tcan4x5x_data_bittiming_const = {
-	.name = DEVICE_NAME,
-	.tseg1_min = 1,
-	.tseg1_max = 32,
-	.tseg2_min = 1,
-	.tseg2_max = 16,
-	.sjw_max = 16,
-	.brp_min = 1,
-	.brp_max = 32,
-	.brp_inc = 1,
-};
-
 static void tcan4x5x_check_wake(struct tcan4x5x_priv *priv)
 {
 	int wake_state = 0;

@@ -469,8 +445,6 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
 	mcan_class->dev = &spi->dev;
 	mcan_class->ops = &tcan4x5x_ops;
 	mcan_class->is_peripheral = true;
-	mcan_class->bit_timing = &tcan4x5x_bittiming_const;
-	mcan_class->data_timing = &tcan4x5x_data_bittiming_const;
 	mcan_class->net->irq = spi->irq;
 
 	spi_set_drvdata(spi, priv);

-- 
2.29.2

In m_can_class_register() the clock is started, but stopped on exit. When
calling m_can_class_unregister(), the clock is stopped a second time.

This patch removes the erroneous m_can_clk_stop() in  m_can_class_unregister().

Fixes: f524f829b75a ("can: m_can: Create a m_can platform framework")
Cc: Dan Murphy <redacted>
Cc: Sriram Dash <redacted>
Reviewed-by: Sean Nyekjaer <redacted>
Link: https://lore.kernel.org/r/20201215103238.524029-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/m_can.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 2c9f12401276..da551fd0f502 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c

@@ -1852,8 +1852,6 @@ EXPORT_SYMBOL_GPL(m_can_class_register);
 void m_can_class_unregister(struct m_can_classdev *cdev)
 {
 	unregister_candev(cdev->net);
-
-	m_can_clk_stop(cdev);
 }
 EXPORT_SYMBOL_GPL(m_can_class_unregister);
 

base-commit: 1f685e6adbbe3c7b1bd9053be771b898d9efa655
-- 
2.29.2

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

The rcar_can driver also supports RZ/G SoC's, update the description to reflect
this.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210104090327.6547-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/rcar/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/rcar/Kconfig b/drivers/net/can/rcar/Kconfig
index 8d36101b78e3..29cabc20109e 100644
--- a/drivers/net/can/rcar/Kconfig
+++ b/drivers/net/can/rcar/Kconfig

@@ -1,10 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0
 config CAN_RCAR
-	tristate "Renesas R-Car CAN controller"
+	tristate "Renesas R-Car and RZ/G CAN controller"
 	depends on ARCH_RENESAS || ARM
 	help
 	  Say Y here if you want to use CAN controller found on Renesas R-Car
-	  SoCs.
+	  or RZ/G SoCs.
 
 	  To compile this driver as a module, choose M here: the module will
 	  be called rcar_can.

-- 
2.29.2

From: Sriram Dash <redacted>

Update Pankaj Sharma as maintainer for mcan mmio device driver as I
will be moving to a different role.

Signed-off-by: Sriram Dash <redacted>
Acked-by: Pankaj Sharma <redacted>
Link: https://lore.kernel.org/r/20210104123134.16930-1-sriram.dash@samsung.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 MAINTAINERS | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 7c1e45c416b1..b15514a770e3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -10847,7 +10847,7 @@ F:	drivers/media/radio/radio-maxiradio*
 
 MCAN MMIO DEVICE DRIVER
 M:	Dan Murphy <dmurphy@ti.com>
-M:	Sriram Dash <sriram.dash@samsung.com>
+M:	Pankaj Sharma <pankj.sharma@samsung.com>
 L:	linux-can@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/can/bosch,m_can.yaml

-- 
2.29.2

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>
---
 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

On Thu,  7 Jan 2021 11:34:45 +0100 Marc Kleine-Budde wrote:

Hello Jakub, hello David,

this is a pull request of 6 patches for net/master.

The first patch is by me for the m_can driver and removes an erroneous
m_can_clk_stop() from the driver's unregister function.

The second patch targets the tcan4x5x driver, is by me, and fixes the bit
timing constant parameters.

The next two patches are by me, target the mcp251xfd driver, and fix a race
condition in the optimized TEF path (which was added in net-next for v5.11).
The similar code in the RX path is changed to look the same, although it
doesn't suffer from the race condition.

A patch by Lad Prabhakar updates the description and help text for the rcar CAN
driver to reflect all supported SoCs.

In the last patch Sriram Dash transfers the maintainership of the m_can driver
to Pankaj Sharma.

Pulled, thanks!