Messages in this thread | | | Date | Tue, 30 Jun 2020 19:00:26 +0200 | From | Michael Walle <> | Subject | Re: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD |
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Am 2020-06-30 18:15, schrieb Oliver Hartkopp: > 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;
[1]
>> [..] >>> 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?
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
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