netdev - [PATCH] flexcan: fix NAPI for bus errors

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Message-ID: <80k4k45csy.fsf@merkur.tec.linutronix.de>
Date:	Tue, 23 Nov 2010 15:34:21 +0100
From:	John Ogness <john.ogness@...utronix.de>
To:	Wolfgang Grandegger <wg@...ndegger.com>
Cc:	kernel@...gutronix.de
Subject: [PATCH] flexcan: fix NAPI for bus errors

If bus error reporting is disabled and bus errors occur, the flexcan
driver will hog the system because it continually re-enables the IRQs
(work_done = 0). This patch changes the driver to only re-enable the
IRQs if some work was actually done. This allows the features of NAPI to
be used for bus errors as well (when bus error reporting is disabled).

This patch is against Linux next-20101123.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 drivers/net/can/flexcan.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- next-20101123-a/drivers/net/can/flexcan.c
+++ next-20101123-b/drivers/net/can/flexcan.c
@@ -535,9 +535,12 @@ static int flexcan_poll(struct napi_stru
 
 	if (work_done < quota) {
 		napi_complete(napi);
-		/* enable IRQs */
-		writel(FLEXCAN_IFLAG_DEFAULT, &regs->imask1);
-		writel(priv->reg_ctrl_default, &regs->ctrl);
+
+		if (work_done > 0) {
+			/* enable IRQs */
+			writel(FLEXCAN_IFLAG_DEFAULT, &regs->imask1);
+			writel(priv->reg_ctrl_default, &regs->ctrl);
+		}
 	}
 
 	return work_done;
--
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