The napi-handler defers c_can reception to softirq, but it is hard to
control the RT priority of the CAN recv end inside a softirq.
Using an irqthread allows precise control of it's RT priority.
Having the quota still around in the IRQ thread allows to restrict
the work_done per cycle.
Signed-off-by: Kurt Van Dijck <dev.kurt@xxxxxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/c_can/c_can.c | 31 ++++++++++---------------------
drivers/net/can/c_can/c_can.h | 1 -
2 files changed, 10 insertions(+), 22 deletions(-)
diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 83ab835..d25a0b7 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -172,9 +172,6 @@
/* Wait for ~1 sec for INIT bit */
#define INIT_WAIT_MS 1000
-/* napi related */
-#define C_CAN_NAPI_WEIGHT C_CAN_MSG_OBJ_RX_NUM
-
/* c_can lec values */
enum c_can_lec_type {
LEC_NO_ERROR = 0,
@@ -1025,9 +1022,9 @@ static int c_can_handle_bus_err(struct net_device *dev,
return 1;
}
-static int c_can_poll(struct napi_struct *napi, int quota)
+static irqreturn_t c_can_thrd(int irq, void *dev_id)
{
- struct net_device *dev = napi->dev;
+ struct net_device *dev = (struct net_device *)dev_id;
struct c_can_priv *priv = netdev_priv(dev);
u16 curr, last = priv->last_status;
int work_done = 0;
@@ -1071,18 +1068,15 @@ static int c_can_poll(struct napi_struct *napi, int quota)
work_done += c_can_handle_bus_err(dev, curr & LEC_MASK);
/* Handle Tx/Rx events. We do this unconditionally */
- work_done += c_can_do_rx_poll(dev, (quota - work_done));
+ work_done += c_can_do_rx_poll(dev, C_CAN_MSG_OBJ_RX_NUM);
c_can_do_tx(dev);
end:
- if (work_done < quota) {
- napi_complete_done(napi, work_done);
- /* enable all IRQs if we are not in bus off state */
- if (priv->can.state != CAN_STATE_BUS_OFF)
- c_can_irq_control(priv, true);
- }
+ /* enable all IRQs if we are not in bus off state */
+ if (priv->can.state != CAN_STATE_BUS_OFF)
+ c_can_irq_control(priv, true);
- return work_done;
+ return work_done ? IRQ_HANDLED : IRQ_NONE;
}
static irqreturn_t c_can_isr(int irq, void *dev_id)
@@ -1101,9 +1095,8 @@ static irqreturn_t c_can_isr(int irq, void *dev_id)
/* disable all interrupts and schedule the NAPI */
c_can_irq_control(priv, false);
- napi_schedule(&priv->napi);
- return IRQ_HANDLED;
+ return IRQ_WAKE_THREAD;
}
static int c_can_open(struct net_device *dev)
@@ -1122,8 +1115,8 @@ static int c_can_open(struct net_device *dev)
}
/* register interrupt handler */
- err = request_irq(dev->irq, &c_can_isr, IRQF_SHARED, dev->name,
- dev);
+ err = request_threaded_irq(dev->irq, &c_can_isr, c_can_thrd,
+ IRQF_SHARED, dev->name, dev);
if (err < 0) {
netdev_err(dev, "failed to request interrupt\n");
goto exit_irq_fail;
@@ -1136,7 +1129,6 @@ static int c_can_open(struct net_device *dev)
can_led_event(dev, CAN_LED_EVENT_OPEN);
- napi_enable(&priv->napi);
/* enable status change, error and module interrupts */
c_can_irq_control(priv, true);
netif_start_queue(dev);
@@ -1158,7 +1150,6 @@ static int c_can_close(struct net_device *dev)
struct c_can_priv *priv = netdev_priv(dev);
netif_stop_queue(dev);
- napi_disable(&priv->napi);
c_can_stop(dev);
free_irq(dev->irq, dev);
close_candev(dev);
@@ -1181,7 +1172,6 @@ struct net_device *alloc_c_can_dev(void)
return NULL;
priv = netdev_priv(dev);
- netif_napi_add(dev, &priv->napi, c_can_poll, C_CAN_NAPI_WEIGHT);
priv->dev = dev;
priv->can.bittiming_const = &c_can_bittiming_const;
@@ -1275,7 +1265,6 @@ void free_c_can_dev(struct net_device *dev)
{
struct c_can_priv *priv = netdev_priv(dev);
- netif_napi_del(&priv->napi);
free_candev(dev);
}
EXPORT_SYMBOL_GPL(free_c_can_dev);
diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index d5567a7..9a8864f 100644
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -194,7 +194,6 @@ struct c_can_raminit {
/* c_can private data structure */
struct c_can_priv {
struct can_priv can; /* must be the first member */
- struct napi_struct napi;
struct net_device *dev;
struct device *device;
atomic_t tx_active;
--
1.8.5.rc3
