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authorAnilKumar Ch <anilkumar@ti.com>2012-05-23 17:45:10 +0530
committerMarc Kleine-Budde <mkl@pengutronix.de>2012-06-03 18:59:19 +0200
commit148c87c89e1a8863d3d965179f3ab1a06490569e (patch)
treedf4bb7144955153698b0515fd84230da2178ace2 /drivers/net/can/c_can
parent617caccebe451716df21c069b079d5936ed7b0f3 (diff)
downloadblackbird-op-linux-148c87c89e1a8863d3d965179f3ab1a06490569e.tar.gz
blackbird-op-linux-148c87c89e1a8863d3d965179f3ab1a06490569e.zip
can: c_can: fix an interrupt thrash issue with c_can driver
This patch fixes an interrupt thrash issue with c_can driver. In c_can_isr() function interrupts are disabled and enabled only in c_can_poll() function. c_can_isr() & c_can_poll() both read the irqstatus flag. However, irqstatus is always read as 0 in c_can_poll() because all C_CAN interrupts are disabled in c_can_isr(). This causes all interrupts to be re-enabled in c_can_poll() which in turn causes another interrupt since the event is not really handled. This keeps happening causing a flood of interrupts. To fix this, read the irqstatus register in isr and use the same cached value in the poll function. Cc: stable@kernel.org # 2.6.39+ Signed-off-by: AnilKumar Ch <anilkumar@ti.com> Acked-by: Wolfgang Grandegger <wg@grandegger.com> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers/net/can/c_can')
-rw-r--r--drivers/net/can/c_can/c_can.c7
-rw-r--r--drivers/net/can/c_can/c_can.h1
2 files changed, 4 insertions, 4 deletions
diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 9ac28df3c896..fa016214c52f 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -952,7 +952,7 @@ static int c_can_poll(struct napi_struct *napi, int quota)
struct net_device *dev = napi->dev;
struct c_can_priv *priv = netdev_priv(dev);
- irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
+ irqstatus = priv->irqstatus;
if (!irqstatus)
goto end;
@@ -1030,12 +1030,11 @@ end:
static irqreturn_t c_can_isr(int irq, void *dev_id)
{
- u16 irqstatus;
struct net_device *dev = (struct net_device *)dev_id;
struct c_can_priv *priv = netdev_priv(dev);
- irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
- if (!irqstatus)
+ priv->irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
+ if (!priv->irqstatus)
return IRQ_NONE;
/* disable all interrupts and schedule the NAPI */
diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index 9b7fbef3d09a..5f32d34af507 100644
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -76,6 +76,7 @@ struct c_can_priv {
unsigned int tx_next;
unsigned int tx_echo;
void *priv; /* for board-specific data */
+ u16 irqstatus;
};
struct net_device *alloc_c_can_dev(void);
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