Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 148c87c8 authored by AnilKumar Ch's avatar AnilKumar Ch Committed by Marc Kleine-Budde
Browse files

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: default avatarAnilKumar Ch <anilkumar@ti.com>
Acked-by: default avatarWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 617cacce

drivers/net/can/c_can/c_can.c

+3 −4
Original line number Diff line number Diff line
@@ -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 @@ static int c_can_poll(struct napi_struct *napi, int quota) 


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 */

drivers/net/can/c_can/c_can.h

+1 −0
Original line number Diff line number Diff line
@@ -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);