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SubjectRe: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD
[+ Oliver]

Hi Joakim,

Am 2020-06-30 04:42, schrieb Joakim Zhang:
>> -----Original Message-----
>> From: Michael Walle <michael@walle.cc>
>> 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 <wg@grandegger.com>; Marc Kleine-Budde
>> <mkl@pengutronix.de>; David S . Miller <davem@davemloft.net>; Jakub
>> Kicinski <kuba@kernel.org>; Joakim Zhang <qiangqing.zhang@nxp.com>;
>> dl-linux-imx <linux-imx@nxp.com>; Michael Walle <michael@walle.cc>
>> 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 <michael@walle.cc>
>> ---
>> 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;
>
>

[..]
> 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.

> 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?

Marc? Oliver?

-michael

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