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Date: Wed, 21 Jan 2015 16:20:25 +0000
From: Andri Yngvason <andri.yngvason@...el.com>
To: "Ahmed S. Darwish" <darwish.07@...il.com>,
Olivier Sobrie <olivier@...rie.be>,
Oliver Hartkopp <socketcan@...tkopp.net>,
"Wolfgang Grandegger" <wg@...ndegger.com>,
Marc Kleine-Budde <mkl@...gutronix.de>
CC: Linux-CAN <linux-can@...r.kernel.org>,
netdev <netdev@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/5] can: kvaser_usb: Consolidate and unify state change
handling
Quoting Ahmed S. Darwish (2015-01-20 21:45:37)
> From: Ahmed S. Darwish <ahmed.darwish@...eo.com>
>
> Replace most of the can interface's state and error counters
> handling with the new can-dev can_change_state() mechanism.
>
> Suggested-by: Andri Yngvason <andri.yngvason@...el.com>
> Signed-off-by: Ahmed S. Darwish <ahmed.darwish@...eo.com>
> ---
> drivers/net/can/usb/kvaser_usb.c | 114 +++++++++++++++++++--------------------
> 1 file changed, 55 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
> index 971c5f9..0386d3f 100644
> --- a/drivers/net/can/usb/kvaser_usb.c
> +++ b/drivers/net/can/usb/kvaser_usb.c
> @@ -620,40 +620,43 @@ static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
> }
>
> static void kvaser_usb_rx_error_update_can_state(struct kvaser_usb_net_priv *priv,
> - const struct kvaser_usb_error_summary *es)
> + const struct kvaser_usb_error_summary *es,
> + struct can_frame *cf)
> {
> struct net_device_stats *stats;
> - enum can_state new_state;
> -
> - stats = &priv->netdev->stats;
> - new_state = priv->can.state;
> + enum can_state cur_state, new_state, tx_state, rx_state;
>
> netdev_dbg(priv->netdev, "Error status: 0x%02x\n", es->status);
>
> - if (es->status & M16C_STATE_BUS_OFF) {
> - priv->can.can_stats.bus_off++;
> + stats = &priv->netdev->stats;
> + new_state = cur_state = priv->can.state;
> +
> + if (es->status & M16C_STATE_BUS_OFF)
> new_state = CAN_STATE_BUS_OFF;
> - } else if (es->status & M16C_STATE_BUS_PASSIVE) {
> - if (priv->can.state != CAN_STATE_ERROR_PASSIVE)
> - priv->can.can_stats.error_passive++;
> + else if (es->status & M16C_STATE_BUS_PASSIVE)
> new_state = CAN_STATE_ERROR_PASSIVE;
> - }
>
> if (es->status == M16C_STATE_BUS_ERROR) {
> - if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
> - ((es->txerr >= 96) || (es->rxerr >= 96))) {
> - priv->can.can_stats.error_warning++;
> + if ((cur_state < CAN_STATE_ERROR_WARNING) &&
> + ((es->txerr >= 96) || (es->rxerr >= 96)))
> new_state = CAN_STATE_ERROR_WARNING;
> - } else if (priv->can.state > CAN_STATE_ERROR_ACTIVE) {
> + else if (cur_state > CAN_STATE_ERROR_ACTIVE)
> new_state = CAN_STATE_ERROR_ACTIVE;
> - }
> }
>
> if (!es->status)
> new_state = CAN_STATE_ERROR_ACTIVE;
>
> + if (new_state != cur_state) {
> + tx_state = (es->txerr >= es->rxerr) ? new_state : 0;
> + rx_state = (es->txerr <= es->rxerr) ? new_state : 0;
> +
> + can_change_state(priv->netdev, cf, tx_state, rx_state);
This (below) is redundant. It doesn't harm but at this point can_change_state
has set priv->can.state to new_state.
> + new_state = priv->can.state;
> + }
> +
> if (priv->can.restart_ms &&
> - (priv->can.state >= CAN_STATE_BUS_OFF) &&
> + (cur_state >= CAN_STATE_BUS_OFF) &&
> (new_state < CAN_STATE_BUS_OFF)) {
> priv->can.can_stats.restarts++;
> }
> @@ -665,18 +668,17 @@ static void kvaser_usb_rx_error_update_can_state(struct kvaser_usb_net_priv *pri
>
> priv->bec.txerr = es->txerr;
> priv->bec.rxerr = es->rxerr;
> - priv->can.state = new_state;
> }
>
> static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
> const struct kvaser_msg *msg)
> {
> - struct can_frame *cf;
> + struct can_frame *cf, tmp_cf = { .can_id = CAN_ERR_FLAG, .can_dlc = CAN_ERR_DLC };
> struct sk_buff *skb;
> struct net_device_stats *stats;
> struct kvaser_usb_net_priv *priv;
> struct kvaser_usb_error_summary es = { };
> - enum can_state old_state;
> + enum can_state old_state, new_state;
>
> switch (msg->id) {
> case CMD_CAN_ERROR_EVENT:
> @@ -721,60 +723,54 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
> }
>
> /* Update all of the can interface's state and error counters before
> - * trying any skb allocation that can actually fail with -ENOMEM.
> + * trying any memory allocation that can actually fail with -ENOMEM.
> + *
> + * We send a temporary stack-allocated error can frame to
> + * can_change_state() for the very same reason.
> + *
> + * TODO: Split can_change_state() responsibility between updating the
> + * can interface's state and counters, and the setting up of can error
> + * frame ID and data to userspace. Remove stack allocation afterwards.
> */
> old_state = priv->can.state;
> - kvaser_usb_rx_error_update_can_state(priv, &es);
> + kvaser_usb_rx_error_update_can_state(priv, &es, &tmp_cf);
> + new_state = priv->can.state;
>
> skb = alloc_can_err_skb(priv->netdev, &cf);
> if (!skb) {
> stats->rx_dropped++;
> return;
> }
> + memcpy(cf, &tmp_cf, sizeof(*cf));
>
> - if (es.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);
> - netif_carrier_off(priv->netdev);
> - } else if (es.status & M16C_STATE_BUS_PASSIVE) {
> - if (old_state != CAN_STATE_ERROR_PASSIVE) {
> - cf->can_id |= CAN_ERR_CRTL;
> -
> - if (es.txerr || es.rxerr)
> - cf->data[1] = (es.txerr > es.rxerr)
> - ? CAN_ERR_CRTL_TX_PASSIVE
> - : CAN_ERR_CRTL_RX_PASSIVE;
> - else
> - cf->data[1] = CAN_ERR_CRTL_TX_PASSIVE |
> - CAN_ERR_CRTL_RX_PASSIVE;
> + if (new_state != old_state) {
> + if (es.status & M16C_STATE_BUS_OFF) {
> + if (!priv->can.restart_ms)
> + kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
> + netif_carrier_off(priv->netdev);
> + }
> +
This block is wrong. The usage of PROT_ACTIVE is based on a misunderstanding.
It's used in some drivers to signify back-to-error-active but its original
meaning is something completely different, AFAIK.
This is handled in can_change_state() using a new CTRL message; namely:
CAN_ERR_CTRL_ACTIVE. The newest version of can-utils is up to date with this.
> + if (es.status == M16C_STATE_BUS_ERROR) {
> + if ((old_state >= CAN_STATE_ERROR_WARNING) ||
> + (es.txerr < 96 && es.rxerr < 96)) {
> + if (old_state > CAN_STATE_ERROR_ACTIVE) {
> + cf->can_id |= CAN_ERR_PROT;
> + cf->data[2] = CAN_ERR_PROT_ACTIVE;
> + }
> + }
> }
> - }
>
> - if (es.status == M16C_STATE_BUS_ERROR) {
> - if ((old_state < CAN_STATE_ERROR_WARNING) &&
> - ((es.txerr >= 96) || (es.rxerr >= 96))) {
> - cf->can_id |= CAN_ERR_CRTL;
> - cf->data[1] = (es.txerr > es.rxerr)
> - ? CAN_ERR_CRTL_TX_WARNING
> - : CAN_ERR_CRTL_RX_WARNING;
> - } else if (old_state > CAN_STATE_ERROR_ACTIVE) {
This is also redundant, and wrong:
> + if (!es.status) {
> cf->can_id |= CAN_ERR_PROT;
> cf->data[2] = CAN_ERR_PROT_ACTIVE;
> }
> - }
>
> - if (!es.status) {
> - cf->can_id |= CAN_ERR_PROT;
> - cf->data[2] = CAN_ERR_PROT_ACTIVE;
> - }
> -
> - if (priv->can.restart_ms &&
> - (old_state >= CAN_STATE_BUS_OFF) &&
> - (priv->can.state < CAN_STATE_BUS_OFF)) {
> - cf->can_id |= CAN_ERR_RESTARTED;
> - netif_carrier_on(priv->netdev);
> + if (priv->can.restart_ms &&
> + (old_state >= CAN_STATE_BUS_OFF) &&
> + (new_state < CAN_STATE_BUS_OFF)) {
> + cf->can_id |= CAN_ERR_RESTARTED;
> + netif_carrier_on(priv->netdev);
> + }
> }
>
> if (es.error_factor) {
> --
> 1.9.1
Looking over the patch again, I've noticed that there are a few things that are
not quite right.
Marc, could you merge the "move bus_off++" patch before you merge this so that I
won't have to incorporate this patch-set into it?
--
Andri
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