From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Michael Walle <michael@walle.cc>, Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Wolfgang Grandegger <wg@grandegger.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD
Date: Tue, 30 Jun 2020 18:15:01 +0200 [thread overview]
Message-ID: <5f6e0843-8504-e941-b6a3-1dc8599db39e@hartkopp.net> (raw)
In-Reply-To: <a42e035c8ee3334a721a089b5f8f0580@walle.cc>
On 30.06.20 07:53, Michael Walle wrote:
> [+ 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(®s->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?
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?
Best,
Oliver
next prev parent reply other threads:[~2020-06-30 16:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-29 18:18 [PATCH 0/2] can: flexcan: small fix and ISO CAN-FD support Michael Walle
2020-06-29 18:18 ` [PATCH 1/2] can: flexcan: use ctrlmode to enable CAN-FD Michael Walle
2020-06-29 18:18 ` [PATCH 2/2] can: flexcan: add support for ISO CAN-FD Michael Walle
2020-06-30 2:42 ` Joakim Zhang
2020-06-30 5:53 ` Michael Walle
2020-06-30 16:15 ` Oliver Hartkopp [this message]
2020-06-30 17:00 ` Michael Walle
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