Subject: Re: [PATCH 2/4] net: can: ifi: Fix TX DLC configuration

From: Marek Vasut <[email-masked]>
Date: Tue, 01 Mar 2016 22:27:20 +0100

On 03/01/2016 07:11 PM, Oliver Hartkopp wrote:

Hi!

> On 02/29/2016 08:59 PM, Marek Vasut wrote:
>> The TX DLC, the transmission length information, was not written
>> into the transmit configuration register. When using the CAN core
>> with different CAN controller, the receiving CAN controller will
>> receive only the ID part of the CAN frame, but no data at all.
>>
>> This patch adds the TX DLC into the register to fix this issue.
>>
>> Signed-off-by: Marek Vasut <[email-masked]>
>> Cc: Marc Kleine-Budde <[email-masked]>
>> Cc: Mark Rutland <[email-masked]>
>> Cc: Oliver Hartkopp <[email-masked]>
>> Cc: Wolfgang Grandegger <[email-masked]>
>> ---
>>  drivers/net/can/ifi_canfd/ifi_canfd.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/net/can/ifi_canfd/ifi_canfd.c b/drivers/net/can/ifi_canfd/ifi_canfd.c
>> index 72f5205..82a33bd 100644
>> --- a/drivers/net/can/ifi_canfd/ifi_canfd.c
>> +++ b/drivers/net/can/ifi_canfd/ifi_canfd.c
>> @@ -774,10 +774,15 @@ static netdev_tx_t ifi_canfd_start_xmit(struct sk_buff *skb,
>>  
>>  	if (priv->can.ctrlmode & (CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO)) {
>>  		if (can_is_canfd_skb(skb)) {
>> +			txdlc |= can_len2dlc(cf->len);
>>  			txdlc |= IFI_CANFD_TXFIFO_DLC_EDL;
>>  			if (cf->flags & CANFD_BRS)
>>  				txdlc |= IFI_CANFD_TXFIFO_DLC_BRS;
>> +		} else {
>> +			txdlc |= cf->len;
>>  		}
>> +	} else {
>> +		txdlc |= cf->len;
>>  	}
> 
> Please use
> 
> 	txdlc |= can_len2dlc(cf->len);
> 
> by default (it works for CAN and CAN FD).
> 
> So that it looks more like:
> 
> 	txdlc |= can_len2dlc(cf->len);

Roger.

> 	if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) && can_is_canfd_skb(skb)) {
> 		txdlc |= IFI_CANFD_TXFIFO_DLC_EDL;
> 		if (cf->flags & CANFD_BRS)
> 			txdlc |= IFI_CANFD_TXFIFO_DLC_BRS;
> 	}
> 
> Testing against CAN_CTRLMODE_FD_NON_ISO is wrong!
> This configuration bit is just for the protocol on the wire and is no
> distinction for CAN / CAN FD.

So CAN_CTRLMODE_FD is always set if the system operates in CAN/FD mode.
And in addition to that, if the system operates in CAN/FD BOSCH mode,
the CAN_CTRLMODE_FD_NON_ISO is set. Do I understand it correctly ?

> Best regards,
> Oliver
> 
>>  
>>  	if (cf->can_id & CAN_RTR_FLAG)
>>

-- 
Best regards,
Marek Vasut