Subject: Re: [PATCH v2] can: kvaser_usb: Add support for Kvaser CAN/USB devices

From: Olivier Sobrie <[email-masked]>
Date: Wed, 8 Aug 2012 08:14:19 +0200

Hi Wolfgang,

On Tue, Aug 07, 2012 at 08:26:38AM +0200, Wolfgang Grandegger wrote:
> On 08/06/2012 07:21 AM, Olivier Sobrie wrote:
> > This driver provides support for several Kvaser CAN/USB devices.
> > Such kind of devices supports up to three can network interfaces.
> 
> s/can/CAN/
> 
> > It has been tested with a Kvaser USB Leaf Light (one network interface)
> > connected to a pch_can interface.
> > The firmware version of the Kvaser device was 2.5.205.
> > 
> > List of Kvaser devices supported by the driver:
> >   - Kvaser Leaf prototype (P010v2 and v3)
> >   - Kvaser Leaf Light (P010v3)
> >   - Kvaser Leaf Professional HS
> >   - Kvaser Leaf SemiPro HS
> >   - Kvaser Leaf Professional LS
> >   - Kvaser Leaf Professional SWC
> >   - Kvaser Leaf Professional LIN
> >   - Kvaser Leaf SemiPro LS
> >   - Kvaser Leaf SemiPro SWC
> >   - Kvaser Memorator II, Prototype
> >   - Kvaser Memorator II HS/HS
> >   - Kvaser USBcan Professional HS/HS
> >   - Kvaser Leaf Light GI
> >   - Kvaser Leaf Professional HS (OBD-II connector)
> >   - Kvaser Memorator Professional HS/LS
> >   - Kvaser Leaf Light "China"
> >   - Kvaser BlackBird SemiPro
> >   - Kvaser OEM Mercury
> >   - Kvaser OEM Leaf
> >   - Kvaser USBcan R
> 
> Impressive list! What CAN controllers are used inside the devices? SJA1000?

I took this list from the Kvaser driver. However I only have a Kvaser
Leaf Light device thus I'm not sure it will work with other ones.
If you prefer I can only let Kvaser Leaf Light instead of the full list.
In my device it looks to be a Renesas M16C controller.

> 
> > Signed-off-by: Olivier Sobrie <[email-masked]>
> > ---
> > Changes since v1:
> >   - added copyrights
> >   - kvaser_usb.h merged into kvaser.c
> >   - added kvaser_usb_get_endpoints to find eindpoints instead of
> >     hardcoding their address
> >   - some cleanup and comestic changes
> >   - fixed issues with errors handling
> >   - fixed restart-ms == 0 case
> >   - removed do_get_berr_counter method since the hardware doens't return
> >     good values for txerr and rxerr.
> > 
> > If someone in the linux-usb mailing can review it, it would be nice.
> > 
> > Concerning the errors, it behaves like that now:
> > 
> > 1) Short-circuit CAN-H and CAN-L and restart-ms = 0
> > 
> > t0: short-circuit + 'cansend can1 123#112233'
> > 
> >   can1  2000008C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  2000008C  [8] 00 30 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  200000C8  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-off
> > 	bus-error
> > 
> > t1: remove short-circuit + 'ip link set can1 type can restart'
> > 
> >   can1  20000100  [8] 00 00 00 00 00 00 00 00   ERRORFRAME
> > 	restarted-after-bus-off
> >   can1  20000004  [8] 00 0C 00 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> 
> Why do we get the last error message? Maybe the firmware does it that
> way (going down passive->warning->active).

It goes in that order: warning -> passive -> bus off -> warning
-> passive -> ...

> 
> > 2) Short-circuit CAN-H and CAN-L and restart-ms = 100
> > 
> > t0: short-circuit + cansend can1 123#112233
> > 
> >   can1  2000008C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  2000008C  [8] 00 30 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  200000C8  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-off
> > 	bus-error
> >   can1  2000018C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> > 	restarted-after-bus-off
> >   can1  2000008C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  2000008C  [8] 00 30 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  200000C8  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-off
> > 	bus-error
> >   ...
> > 
> >   can1  2000018C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> > 	restarted-after-bus-off
> >   can1  2000008C  [8] 00 0C 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-warning,tx-error-warning}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> >   can1  2000008C  [8] 00 30 90 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> > 	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
> > 	bus-error
> > 
> > t1: remove short-circuit
> > 
> >   can1  123  [3] 11 22 33
> >   can1  20000008  [8] 00 00 40 00 00 00 00 00   ERRORFRAME
> > 	protocol-violation{{back-to-error-active}{}}
> 
> The order is still inverted but likely the firmware is doing it that way.

Indeed the firmware does it that way: it sends the acknwledge of the
frame beofre the state change. I can avoid that behavior by checking the
state in the acknowledge frame and send the restart frame if the bus was
off.

> 
> > 3) CAN-H and CAN-L disconnected
> > 
> > t0: CAN-H and CAN-L disconnected + cansend can1 123#112233
> > 
> >   can1  20000004  [8] 00 30 00 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> >   can1  2000008C  [8] 00 30 80 1B 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> > 	protocol-violation{{error-on-tx}{acknowledge-delimiter}}
> > 	bus-error
> > 
> > t1: CAN-H and CAN-L reconnected
> > 
> >   can1  123  [3] 11 22 33
> >   can1  20000004  [8] 00 30 00 00 00 00 00 00   ERRORFRAME
> > 	controller-problem{rx-error-passive,tx-error-passive}
> 
> Why do we get an error-passive message? Now I will have a closer look to
> the code...

The firmware sends a CMD_CAN_ERROR_EVENT with the passive bit set...

> > +static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
> > +				const struct kvaser_msg *msg)
> > +{
> > +	struct can_frame *cf;
> > +	struct sk_buff *skb;
> > +	struct net_device_stats *stats;
> > +	struct kvaser_usb_net_priv *priv;
> > +	unsigned int new_state;
> > +	u8 channel, status;
> > +
> > +	if (msg->id == CMD_CAN_ERROR_EVENT) {
> > +		channel = msg->u.error_event.channel;
> > +		status =  msg->u.error_event.status;
> > +	} else {
> > +		channel = msg->u.chip_state_event.channel;
> > +		status =  msg->u.chip_state_event.status;
> > +	}
> > +
> > +	if (channel >= dev->nchannels) {
> > +		dev_err(dev->udev->dev.parent,
> > +			"Invalid channel number (%d)\n", channel);
> > +		return;
> > +	}
> > +
> > +	priv = dev->nets[channel];
> > +	stats = &priv->netdev->stats;
> > +
> > +	if (status & M16C_STATE_BUS_RESET) {
> > +		kvaser_usb_unlink_tx_urbs(priv);
> > +		return;
> > +	}
> > +	skb = alloc_can_err_skb(priv->netdev, &cf);
> > +	if (!skb) {
> > +		stats->rx_dropped++;
> > +		return;
> 
> Cleanup? kvaser_usb_unlink_tx_urbs()?

If I get the M16C_STATE_BUS_RESET I'll not receive the ack frames anymore.
I need to set the context->echo_index back to MAX_TX_URBS to not loose tx
urbs.
By the way I think a can_free_echo_skb() is missing...

> 
> > +	}
> > +
> > +	if (status & M16C_STATE_BUS_OFF) {
> > +		cf->can_id |= CAN_ERR_BUSOFF;
> > +
> > +		if (!priv->can.restart_ms)
> > +			kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
> > +
> > +		if (!priv->can.state != CAN_ERR_BUSOFF) {
> > +			priv->can.can_stats.bus_off++;
> > +			netif_carrier_off(priv->netdev);
> > +		}
> > +
> > +		new_state = CAN_STATE_BUS_OFF;
> > +	} else if (status & M16C_STATE_BUS_PASSIVE) {
> > +		cf->can_id |= CAN_ERR_CRTL;
> > +		cf->data[1] = CAN_ERR_CRTL_TX_PASSIVE |
> > +			      CAN_ERR_CRTL_RX_PASSIVE;
> 
> State changes should only be report when the state really changes.
> Therefore it should go under the if block below.

Ok. Is it possible to get such sequence:
can1  20000088  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
can1  20000088  [8] 00 10 90 00 00 00 00 00   ERRORFRAME
can1  20000088  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
can1  20000088  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
can1  20000088  [8] 00 00 90 00 00 00 00 00   ERRORFRAME

2 questions:
1) If the bus is still in CAN_ERR_CRTL_RX_PASSIVE after the second frame,
   shouldn't we let the corresponding bit set, 0x10?
2) Can we send multiple times same frame wih same error bits set?

> 
> > +		if (priv->can.state != CAN_STATE_ERROR_PASSIVE)
> > +			priv->can.can_stats.error_passive++;
> > +
> > +		new_state = CAN_STATE_ERROR_PASSIVE;
> > +	} else if (status & M16C_STATE_BUS_ERROR) {
> 
> Hm, strange, a bus error is not a state change. You use here if...else
> if... Isn't it possible that more than one bit is set.

Indeed it is possible to have multiple bits set.
e.g. M16C_STATE_BUS_PASSIVE + M16C_STATE_BUS_ERROR or M16C_STATE_BUS_OFF + M16C_STATE_BUS_ERROR.

What error should I report in case of M16C_STATE_BUS_ERROR?

> 
> > +		cf->can_id |= CAN_ERR_CRTL;
> > +		cf->data[1] = CAN_ERR_CRTL_TX_WARNING |
> > +			      CAN_ERR_CRTL_RX_WARNING;
> 
> See above.
> 
> > +		if (priv->can.state != CAN_STATE_ERROR_WARNING)
> > +			priv->can.can_stats.error_warning++;
> > +
> > +		new_state = CAN_STATE_ERROR_WARNING;
> > +	} else {
> > +		cf->can_id |= CAN_ERR_PROT;
> > +		cf->data[2] = CAN_ERR_PROT_ACTIVE;
> > +
> > +		new_state = CAN_STATE_ERROR_ACTIVE;
> > +	}
> > +
> > +	if (priv->can.restart_ms &&
> > +	    (priv->can.state >= CAN_STATE_BUS_OFF) &&
> > +	    (new_state < CAN_STATE_BUS_OFF)) {
> > +		cf->can_id |= CAN_ERR_RESTARTED;
> > +		priv->can.can_stats.restarts++;
> > +		netif_carrier_on(priv->netdev);
> > +	}
> > +
> > +	if (msg->id == CMD_CAN_ERROR_EVENT) {
> > +		u8 error_factor = msg->u.error_event.error_factor;
> > +
> > +		priv->can.can_stats.bus_error++;
> > +		stats->rx_errors++;
> > +
> > +		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> > +
> > +		if (error_factor & M16C_EF_ACKE)
> > +			cf->data[3] |= (CAN_ERR_PROT_LOC_ACK |
> > +					CAN_ERR_PROT_LOC_ACK_DEL);
> > +		if (error_factor & M16C_EF_CRCE)
> > +			cf->data[3] |= (CAN_ERR_PROT_LOC_CRC_SEQ |
> > +					CAN_ERR_PROT_LOC_CRC_DEL);
> > +		if (error_factor & M16C_EF_FORME)
> > +			cf->data[2] |= CAN_ERR_PROT_FORM;
> > +		if (error_factor & M16C_EF_STFE)
> > +			cf->data[2] |= CAN_ERR_PROT_STUFF;
> > +		if (error_factor & M16C_EF_BITE0)
> > +			cf->data[2] |= CAN_ERR_PROT_BIT0;
> > +		if (error_factor & M16C_EF_BITE1)
> > +			cf->data[2] |= CAN_ERR_PROT_BIT1;
> > +		if (error_factor & M16C_EF_TRE)
> > +			cf->data[2] |= CAN_ERR_PROT_TX;
> > +	}
> > +
> > +	priv->can.state = new_state;
> > +
> > +	if (!memcmp(cf, &priv->cf_err_old, sizeof(*cf))) {
> > +		kfree_skb(skb);
> > +		return;
> > +	}
> 
> Hm, the firmware seems not to clear error conditions? Anyway, state
> change and error reporting is magic on many CAN controllers. Just the
> SJA1000 is doing it nicely.

I added it to prevent sending two times the same error. It happens that
the firmware sends multiple times the same error message.

> 
> > +	netif_rx(skb);
> > +
> > +	priv->cf_err_old = *cf;
> > +
> > +	stats->rx_packets++;
> > +	stats->rx_bytes += cf->can_dlc;
> > +}
> > +
> > +static void kvaser_usb_rx_can_msg(const struct kvaser_usb *dev,
> > +				  const struct kvaser_msg *msg)
> > +{
> > +	struct kvaser_usb_net_priv *priv;
> > +	struct can_frame *cf;
> > +	struct sk_buff *skb;
> > +	struct net_device_stats *stats;
> > +	u8 channel = msg->u.rx_can.channel;
> > +
> > +	if (channel >= dev->nchannels) {
> > +		dev_err(dev->udev->dev.parent,
> > +			"Invalid channel number (%d)\n", channel);
> > +		return;
> > +	}
> > +
> > +	priv = dev->nets[channel];
> > +	stats = &priv->netdev->stats;
> > +
> > +	skb = alloc_can_skb(priv->netdev, &cf);
> > +	if (skb == NULL) {
> 
> s/skb == NULL)/!skb/ ?
> 
> > +		stats->tx_dropped++;
> > +		return;
> > +	}
> > +
> > +	cf->can_id = ((msg->u.rx_can.msg[0] & 0x1f) << 6) |
> > +		     (msg->u.rx_can.msg[1] & 0x3f);
> > +	cf->can_dlc = get_can_dlc(msg->u.rx_can.msg[5]);
> > +
> > +	if (msg->id == CMD_RX_EXT_MESSAGE) {
> > +		cf->can_id <<= 18;
> > +		cf->can_id |= ((msg->u.rx_can.msg[2] & 0x0f) << 14) |
> > +			      ((msg->u.rx_can.msg[3] & 0xff) << 6) |
> > +			      (msg->u.rx_can.msg[4] & 0x3f);
> > +		cf->can_id |= CAN_EFF_FLAG;
> > +	}
> > +
> > +	if (msg->u.rx_can.flag & MSG_FLAG_REMOTE_FRAME) {
> > +		cf->can_id |= CAN_RTR_FLAG;
> > +	} else if (msg->u.rx_can.flag & (MSG_FLAG_ERROR_FRAME |
> > +					 MSG_FLAG_NERR)) {
> > +		cf->can_id |= CAN_ERR_FLAG;
> > +		cf->can_dlc = CAN_ERR_DLC;
> > +		cf->data[1] = CAN_ERR_CRTL_UNSPEC;
> 
> What is the meaning of such errors? A comment, netdev_err() or
> netdev_dbg() would be nice.

I never reached this error with the hardware I've... I don't know what's
the meaning of this flag... I will add a trace.

> 
> > +
> > +		stats->rx_errors++;
> > +	} else if (msg->u.rx_can.flag & MSG_FLAG_OVERRUN) {
> > +		cf->can_id = CAN_ERR_FLAG | CAN_ERR_CRTL;
> > +		cf->can_dlc = CAN_ERR_DLC;
> > +		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> > +
> > +		stats->rx_over_errors++;
> > +		stats->rx_errors++;
> > +	} else if (!msg->u.rx_can.flag) {
> > +		memcpy(cf->data, &msg->u.rx_can.msg[6], cf->can_dlc);
> > +	} else {
> > +		kfree_skb(skb);
> > +		return;
> > +	}
> > +
> > +	netif_rx(skb);
> > +
> > +	stats->rx_packets++;
> > +	stats->rx_bytes += cf->can_dlc;
> > +}
> > +

I'll fix all others small things you mentionned.
Thank you!

-- 
Olivier