Am 2020-06-30 18:15, schrieb Oliver Hartkopp:

On 30.06.20 07:53, Michael Walle wrote:

quoted

[+ Oliver]

Hi Joakim,

Am 2020-06-30 04:42, schrieb Joakim Zhang:

quoted

quoted

-----Original Message-----
From: Michael Walle <redacted>
Sent: 2020年6月30日 2:18
To: linux-can@vger.kernel.org; netdev@vger.kernel.org;
linux-kernel@vger.kernel.org
Cc: Wolfgang Grandegger <redacted>; Marc Kleine-Budde
[off-list ref]; David S . Miller [off-list ref]; Jakub
Kicinski [off-list ref]; Joakim Zhang [off-list ref];
dl-linux-imx [off-list ref]; Michael Walle [off-list ref]
Subject: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD

Up until now, the controller used non-ISO CAN-FD mode, although it 
supports it.
Add support for ISO mode, too. By default the hardware is in non-ISO 
mode and
an enable bit has to be explicitly set.

Signed-off-by: Michael Walle <redacted>
---
 drivers/net/can/flexcan.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c 

index
183e094f8d66..a92d3cdf4195 100644

--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c

@@ -94,6 +94,7 @@

 #define FLEXCAN_CTRL2_MRP        BIT(18)
 #define FLEXCAN_CTRL2_RRS        BIT(17)
 #define FLEXCAN_CTRL2_EACEN        BIT(16)
+#define FLEXCAN_CTRL2_ISOCANFDEN    BIT(12)

 /* FLEXCAN memory error control register (MECR) bits */
 #define FLEXCAN_MECR_ECRWRDIS        BIT(31)

@@ -1344,14 +1345,25 @@ static int flexcan_chip_start(struct 

net_device
*dev)
     else
         reg_mcr |= FLEXCAN_MCR_SRX_DIS;

-    /* MCR - CAN-FD */
-    if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
+    /* MCR, CTRL2
+     *
+     * CAN-FD mode
+     * ISO CAN-FD mode
+     */
+    reg_ctrl2 = priv->read(&regs->ctrl2);
+    if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
         reg_mcr |= FLEXCAN_MCR_FDEN;
-    else
+        reg_ctrl2 |= FLEXCAN_CTRL2_ISOCANFDEN;
+    } else {
         reg_mcr &= ~FLEXCAN_MCR_FDEN;
+    }
+
+    if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
+        reg_ctrl2 &= ~FLEXCAN_CTRL2_ISOCANFDEN;

[1]

quoted

[..]

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ip link set can0 up type can bitrate 1000000 dbitrate 5000000 fd on
ip link set can0 up type can bitrate 1000000 dbitrate 5000000 fd on \
   fd-non-iso on

vs.

quoted

ip link set can0 up type can bitrate 1000000 dbitrate 5000000 
fd-non-iso on

I haven't found anything if CAN_CTRLMODE_FD_NON_ISO depends on
CAN_CTRLMODE_FD. I.e. wether CAN_CTRLMODE_FD_NON_ISO can only be set 
if
CAN_CTRLMODE_FD is also set.

Only the following piece of code, which might be a hint that you
have to set CAN_CTRLMODE_FD if you wan't to use 
CAN_CTRLMODE_FD_NON_ISO:

drivers/net/can/dev.c:
   /* do not check for static fd-non-iso if 'fd' is disabled */
   if (!(maskedflags & CAN_CTRLMODE_FD))
           ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;

If CAN_CTRLMODE_FD_NON_ISO can be set without CAN_CTRLMODE_FD, what
should be the mode if both are set at the same time?

CAN_CTRLMODE_FD_NON_ISO is only relevant when CAN_CTRLMODE_FD is set.

So in the example from above

ip link set can0 up type can bitrate 1000000 dbitrate 5000000 
fd-non-iso on

either the setting of 'dbitrate 5000000' and 'fd-non-iso on' is 
pointless.

When switching to FD-mode with 'fd on' the FD relevant settings need
to be applied.

FD ISO is the default.

Did this help or did I get anything wrong?

Thanks for the explanation. Yes this helped a great deal and this
patch should be correct; it sets ISO mode if CAN_CTRLMODE_FD is set
and masks it again if CAN_CTRLMODE_FD_NON_ISO is set. See [1].

-michael