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Date: Mon, 09 Sep 2013 12:05:26 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Benedikt Spranger <b.spranger@...utronix.de>
CC: netdev@...r.kernel.org,
Alexander Frank <Alexander.Frank@...rspaecher.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Holger Dengler <dengler@...utronix.de>,
"linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
Subject: Re: [PATCH 11/16] c_can: stop netqueue if hardware is busy
On 09/09/2013 09:25 AM, Benedikt Spranger wrote:
> Unlike other network devices the FlexCard do not support interrupts on TX.
> Emulate the TX interrupt by polling the MOTRX registers and restart the
> netqueue if one or more message object is available for transtition of CAN
> frames.
>
> Signed-off-by: Benedikt Spranger <b.spranger@...utronix.de>
> ---
> drivers/net/can/c_can/c_can.c | 61 ++++++++++++++++++++++++++++++++++++++++---
> drivers/net/can/c_can/c_can.h | 4 +++
> 2 files changed, 62 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> index 46d741d..02f7c89 100644
> --- a/drivers/net/can/c_can/c_can.c
> +++ b/drivers/net/can/c_can/c_can.c
> @@ -550,18 +550,66 @@ static void c_can_inval_msg_object(struct net_device *dev, int iface, int objno)
>
> static inline int c_can_is_next_tx_obj_busy(struct c_can_priv *priv, int objno)
> {
> - int val = c_can_read_reg32(priv, C_CAN_TXRQST1_REG);
> + int val = c_can_read_reg32(priv, C_CAN_TXRQST1_REG + (objno / 32) * 4);
>
> /*
> * as transmission request register's bit n-1 corresponds to
> * message object n, we need to handle the same properly.
> */
> - if (val & (1 << (objno - 1)))
> + if (val & (1 << ((objno % 32) - 1)))
> return 1;
>
> return 0;
> }
>
> +static void c_can_motrx_add_timer(struct net_device *dev)
> +{
> + struct c_can_priv *priv = netdev_priv(dev);
> +
> + priv->timer.expires = round_jiffies_relative(1);
> + add_timer(&priv->timer);
> +}
> +
> +static void c_can_motrx_poll(unsigned long data)
> +{
> + struct net_device *dev = (struct net_device *)data;
> + struct c_can_priv *priv = netdev_priv(dev);
> + u32 val, empty = 0;
> + int i;
> +
> + for (i = 0; i < C_CAN_MOTRX_NR; i++) {
> + val = c_can_read_reg32(priv, C_CAN_TXRQST1_REG + i * 4);
> +
> + if (val < priv->motrx[i]) {
> + netif_wake_queue(dev);
> + return;
> + }
> +
> + empty |= val;
> + }
> +
> + if (!empty) {
> + netif_wake_queue(dev);
> + return;
> + }
> +
> + c_can_motrx_add_timer(dev);
> +}
> +
> +static void c_can_motrx_monitor(struct net_device *dev)
> +{
> + struct c_can_priv *priv = netdev_priv(dev);
> + int i;
> +
> + if (priv->type != BOSCH_D_CAN_FLEXCARD)
> + return;
> +
> + for (i = 0; i < C_CAN_MOTRX_NR; i++)
> + priv->motrx[i] = c_can_read_reg32(priv,
> + C_CAN_TXRQST1_REG + i * 4);
> + c_can_motrx_add_timer(dev);
> +}
> +
> static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
> struct net_device *dev)
> {
> @@ -582,6 +630,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
> if (readl(priv->base + FC_TXFIFO_STAT) &
> FC_TXFIFO_STAT_FULL) {
> netif_stop_queue(dev);
> + c_can_motrx_monitor(dev);
> return NETDEV_TX_BUSY;
> }
>
> @@ -619,8 +668,10 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
> * if the next TX message object is still in use
> */
> if (c_can_is_next_tx_obj_busy(priv, get_tx_next_msg_obj(priv))
> - || ((priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) == 0))
> + || ((priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) == 0)) {
> netif_stop_queue(dev);
> + c_can_motrx_monitor(dev);
> + }
> }
>
> return NETDEV_TX_OK;
> @@ -1272,6 +1323,7 @@ static int c_can_close(struct net_device *dev)
> {
> struct c_can_priv *priv = netdev_priv(dev);
>
> + del_timer_sync(&priv->timer);
> netif_stop_queue(dev);
> napi_disable(&priv->napi);
> c_can_stop(dev);
> @@ -1306,6 +1358,9 @@ struct net_device *alloc_c_can_dev(void)
> CAN_CTRLMODE_LISTENONLY |
> CAN_CTRLMODE_BERR_REPORTING;
> spin_lock_init(&priv->lock);
> + priv->timer.function = c_can_motrx_poll;
> + priv->timer.data = (unsigned long) dev;
> + init_timer_deferrable(&priv->timer);
>
> return dev;
> }
> diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> index beea437..6d0f805 100644
> --- a/drivers/net/can/c_can/c_can.h
> +++ b/drivers/net/can/c_can/c_can.h
> @@ -153,6 +153,8 @@ enum c_can_dev_id {
> BOSCH_D_CAN_FLEXCARD,
> };
>
> +#define C_CAN_MOTRX_NR 1
Are there reasons to have C_CAN_MOTRX_NR != 1? If not, please remove the
array and make code more clean.
> /* c_can private data structure */
> struct c_can_priv {
> struct can_priv can; /* must be the first member */
> @@ -176,6 +178,8 @@ struct c_can_priv {
> unsigned int instance;
> void (*raminit) (const struct c_can_priv *priv, bool enable);
> spinlock_t lock;
> + struct timer_list timer;
> + u32 motrx[C_CAN_MOTRX_NR];
> };
>
> struct net_device *alloc_c_can_dev(void);
>
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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