On 5/9/13 11:19 AM, David Hauweele wrote:
The transceiver may fail under heavy traffic when a frame is transmitted
while receiving another frame.
This patch uses a mutex to separate the transmission and reception of
frames along with a secondary working queue to avoid a deadlock while
waiting for the transmission interrupt.
Have you observed this failure? I have put this kind of thing in before
(several times actually) but ultimately convinced myself each time that
it was not necessary. I'm happy to be shown wrong.
Signed-off-by: David Hauweele <da...@hauweele.net>
---
drivers/net/ieee802154/mrf24j40.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ieee802154/mrf24j40.c
b/drivers/net/ieee802154/mrf24j40.c
index ede3ce4..1e3ddf3 100644
--- a/drivers/net/ieee802154/mrf24j40.c
+++ b/drivers/net/ieee802154/mrf24j40.c
@@ -82,8 +82,10 @@ struct mrf24j40 {
struct ieee802154_dev *dev;
struct mutex buffer_mutex; /* only used to protect buf */
+ struct mutex txrx_mutex; /* avoid transmission while receiving a frame
*/
struct completion tx_complete;
struct work_struct irqwork;
+ struct work_struct rxwork;
u8 *buf; /* 3 bytes. Used for SPI single-register transfers. */
};
@@ -353,6 +355,8 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct
sk_buff *skb)
/* Set TXNACKREQ if the ACK bit is set in the packet. */
if (skb->data[0] & IEEE802154_FC_ACK_REQ)
val |= 0x4;
+
+ mutex_lock(&devrec->txrx_mutex);
write_short_reg(devrec, REG_TXNCON, val);
INIT_COMPLETION(devrec->tx_complete);
@@ -361,6 +365,9 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct
sk_buff *skb)
ret = wait_for_completion_interruptible_timeout(
&devrec->tx_complete,
5 * HZ);
+
+ mutex_unlock(&devrec->txrx_mutex);
+
if (ret == -ERESTARTSYS)
goto err;
if (ret == 0) {
@@ -535,6 +542,8 @@ static int mrf24j40_handle_rx(struct mrf24j40 *devrec)
int ret = 0;
struct sk_buff *skb;
+ mutex_lock(&devrec->txrx_mutex);
+
/* Turn off reception of packets off the air. This prevents the
* device from overwriting the buffer while we're reading it. */
ret = read_short_reg(devrec, REG_BBREG1, &val);
@@ -575,6 +584,8 @@ out:
val &= ~0x4; /* Clear RXDECINV */
write_short_reg(devrec, REG_BBREG1, val);
+ mutex_unlock(&devrec->txrx_mutex);
+
return ret;
}
@@ -616,12 +627,19 @@ static void mrf24j40_isrwork(struct work_struct *work)
/* Check for Rx */
if (intstat & 0x8)
- mrf24j40_handle_rx(devrec);
+ schedule_work(&devrec->rxwork);
mrf24f40_isrwork() is already called from a workqueue.
out:
enable_irq(devrec->spi->irq);
}
+static void mrf24j40_rxwork(struct work_struct *work)
+{
+ struct mrf24j40 *devrec = container_of(work, struct mrf24j40, rxwork);
+
+ mrf24j40_handle_rx(devrec);
+}
+
static int mrf24j40_probe(struct spi_device *spi)
{
int ret = -ENOMEM;
@@ -648,8 +666,10 @@ static int mrf24j40_probe(struct spi_device *spi)
spi->max_speed_hz = MAX_SPI_SPEED_HZ;
mutex_init(&devrec->buffer_mutex);
+ mutex_init(&devrec->txrx_mutex);
init_completion(&devrec->tx_complete);
INIT_WORK(&devrec->irqwork, mrf24j40_isrwork);
+ INIT_WORK(&devrec->rxwork, mrf24j40_rxwork);
devrec->spi = spi;
spi_set_drvdata(spi, devrec);
--
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