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Commit d3cd1565 authored by Marc Kleine-Budde's avatar Marc Kleine-Budde
Browse files

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: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
Acked-by: default avatarWolfgang Grandegger <wg@grandegger.com>
parent 7e15de3a

drivers/net/can/mcp251x.c

+13 −2
Original line number Diff line number Diff line
@@ -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);