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Date: Tue, 30 Jun 2020 18:15:01 +0200 From: Oliver Hartkopp <socketcan@...tkopp.net> To: Michael Walle <michael@...le.cc>, Joakim Zhang <qiangqing.zhang@....com> Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, Wolfgang Grandegger <wg@...ndegger.com>, Marc Kleine-Budde <mkl@...gutronix.de>, "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, dl-linux-imx <linux-imx@....com> Subject: Re: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD 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@...le.cc> >>> Sent: 2020年6月30日 2:18 >>> To: linux-can@...r.kernel.org; netdev@...r.kernel.org; >>> linux-kernel@...r.kernel.org >>> Cc: Wolfgang Grandegger <wg@...ndegger.com>; Marc Kleine-Budde >>> <mkl@...gutronix.de>; David S . Miller <davem@...emloft.net>; Jakub >>> Kicinski <kuba@...nel.org>; Joakim Zhang <qiangqing.zhang@....com>; >>> dl-linux-imx <linux-imx@....com>; Michael Walle <michael@...le.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@...le.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
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