From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Walle Subject: Re: [PATCH 2/2] can: flexcan: add support for ISO CAN-FD Date: Tue, 30 Jun 2020 19:00:26 +0200 Message-ID: References: <20200629181809.25338-1-michael@walle.cc> <20200629181809.25338-3-michael@walle.cc> <5f6e0843-8504-e941-b6a3-1dc8599db39e@hartkopp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <5f6e0843-8504-e941-b6a3-1dc8599db39e@hartkopp.net> Sender: netdev-owner@vger.kernel.org To: Oliver Hartkopp Cc: Joakim Zhang , 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 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 >>>> 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; [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