From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: Re: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD Date: Tue, 30 Jun 2020 18:15:01 +0200 Message-ID: <5f6e0843-8504-e941-b6a3-1dc8599db39e@hartkopp.net> References: <20200629181809.25338-1-michael@walle.cc> <20200629181809.25338-3-michael@walle.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Michael Walle , Joakim Zhang Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Wolfgang Grandegger , Marc Kleine-Budde , "David S . Miller" , Jakub Kicinski , dl-linux-imx List-Id: linux-can.vger.kernel.org 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 >>> 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 ; Marc Kleine-Budde >>> ; David S . Miller ; Jakub >>> Kicinski ; Joakim Zhang ; >>> dl-linux-imx ; Michael Walle >>> 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 >>> --- >>>  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