From: Jan Altenberg <jan@linutronix.de>
Date: Mon, 28 Mar 2011 01:24:10 +0000 (-0700)
Subject: can: c_can: Fix tx_bytes accounting
X-Git-Tag: v2.6.39-rc1~9^2~18
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc760b375e50a47847d4942811bd9679beeb5535;p=pandora-kernel.git

can: c_can: Fix tx_bytes accounting

The current SocketCAN implementation for the Bosch c_can cell doesn't
account the TX bytes correctly, because it calls
c_can_inval_msg_object() (which clears the msg ctrl register) before
reading the DLC value:

for (/* nix */; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) {
        msg_obj_no = get_tx_echo_msg_obj(priv);
        c_can_inval_msg_object(dev, 0, msg_obj_no);
        val = c_can_read_reg32(priv, &priv->regs->txrqst1);
        if (!(val & (1 << msg_obj_no))) {
                can_get_echo_skb(dev,
                                msg_obj_no - C_CAN_MSG_OBJ_TX_FIRST);
                stats->tx_bytes += priv->read_reg(priv,
                                &priv->regs->ifregs[0].msg_cntrl)
                                & IF_MCONT_DLC_MASK;
                stats->tx_packets++;
        }
}

So, we will always read 0 for the DLC value and "ifconfig" will report
*0* TX Bytes.

The fix is quite easy: Just move c_can_inval_msg_object() to the end of
the if() statement. So:
      * We only call c_can_inval_msg_object() if the message was
        actually transmitted
      * We read out the DLC value _before_ clearing the msg ctrl
        register

Signed-off-by: Jan Altenberg <jan@linutronix.de>
Acked-by: Kurt Van Dijck <kurt.van.dijck@eia.be>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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