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authorMarc Kleine-Budde <mkl@pengutronix.de>2010-09-28 10:18:34 +0200
committerMarc Kleine-Budde <mkl@pengutronix.de>2010-10-18 11:19:42 +0200
commitd3cd15657516141adce387810be8cb377baf020e (patch)
treef85a4b2ab4b8bd7f532ccf93e56dc1cade87eb6e /drivers/net/can
parent7e15de3a73899903f33975b1ce57cf59c616d1d9 (diff)
can: mcp251x: write intf only when needed
This patch introduces a variable "clear_intf" that hold the bits that should be cleared. Only read-modify-write register if "clear_intf" is set. Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Diffstat (limited to 'drivers/net/can')
-rw-r--r--drivers/net/can/mcp251x.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index 7e2f951002a..f5e2edd09ce 100644
--- a/drivers/net/can/mcp251x.c
+++ b/drivers/net/can/mcp251x.c
@@ -125,6 +125,8 @@
# define CANINTF_TX0IF 0x04
# define CANINTF_RX1IF 0x02
# define CANINTF_RX0IF 0x01
+# define CANINTF_ERR_TX \
+ (CANINTF_ERRIF | CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)
#define EFLG 0x2d
# define EFLG_EWARN 0x01
# define EFLG_RXWAR 0x02
@@ -769,10 +771,12 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
while (!priv->force_quit) {
enum can_state new_state;
u8 intf, eflag;
+ u8 clear_intf = 0;
int can_id = 0, data1 = 0;
mcp251x_read_2regs(spi, CANINTF, &intf, &eflag);
+ /* receive buffer 0 */
if (intf & CANINTF_RX0IF) {
mcp251x_hw_rx(spi, 0);
/* Free one buffer ASAP */
@@ -780,10 +784,17 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
0x00);
}
- if (intf & CANINTF_RX1IF)
+ /* receive buffer 1 */
+ if (intf & CANINTF_RX1IF) {
mcp251x_hw_rx(spi, 1);
+ clear_intf |= CANINTF_RX1IF;
+ }
- mcp251x_write_bits(spi, CANINTF, intf, 0x00);
+ /* any error or tx interrupt we need to clear? */
+ if (intf & CANINTF_ERR_TX)
+ clear_intf |= intf & CANINTF_ERR_TX;
+ if (clear_intf)
+ mcp251x_write_bits(spi, CANINTF, clear_intf, 0x00);
if (eflag)
mcp251x_write_bits(spi, EFLG, eflag, 0x00);