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Commit e91c021c authored by Mark A. Greer's avatar Mark A. Greer Committed by Greg Kroah-Hartman
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[PATCH] i2c: i2c-mv64xxx fix transaction abortion 



When the i2c-mv64xxx i2c driver is signalled to abort a transaction,
it aborts it immediately by issuing a stop condition on the bus.
This violates the i2c protocol and can cause what appears to be an i2c
bus hang.  This patch delays issuing the stop condition until the i2c
device can reasonably expect a stop condition.

Also includes a minor fixup.

Signed-off-by: default avatarMark A. Greer <mgreer@mvista.com>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 7c72ccf0

drivers/i2c/busses/i2c-mv64xxx.c

+15 −18
Original line number Diff line number Diff line 
/*

 * drivers/i2c/busses/i2c-mv64xxx.c

 * 

 * Driver for the i2c controller on the Marvell line of host bridges for MIPS

 * and PPC (e.g, gt642[46]0, mv643[46]0, mv644[46]0).

 *
@@ -65,7 +63,6 @@ enum { 
	MV64XXX_I2C_STATE_WAITING_FOR_ADDR_2_ACK,

	MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_ACK,

	MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_DATA,

	MV64XXX_I2C_STATE_ABORTING,

};



/* Driver actions */
@@ -85,6 +82,7 @@ struct mv64xxx_i2c_data { 
	int			irq;

	u32			state;

	u32			action;

	u32			aborting;

	u32			cntl_bits;

	void __iomem		*reg_base;

	u32			reg_base_p;
@@ -122,12 +120,6 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status) 
		return;

	}



	if (drv_data->state == MV64XXX_I2C_STATE_ABORTING) {

		drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;

		drv_data->state = MV64XXX_I2C_STATE_IDLE;

		return;

	}



	/* The status from the ctlr [mostly] tells us what to do next */

	switch (status) {

	/* Start condition interrupt */
@@ -148,14 +140,16 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status) 
		/* FALLTHRU */

	case MV64XXX_I2C_STATUS_MAST_WR_ADDR_2_ACK: /* 0xd0 */

	case MV64XXX_I2C_STATUS_MAST_WR_ACK: /* 0x28 */

		if (drv_data->bytes_left > 0) {

		if ((drv_data->bytes_left == 0)

				|| (drv_data->aborting

					&& (drv_data->byte_posn != 0))) {

			drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;

			drv_data->state = MV64XXX_I2C_STATE_IDLE;

		} else {

			drv_data->action = MV64XXX_I2C_ACTION_SEND_DATA;

			drv_data->state =

				MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_ACK;

			drv_data->bytes_left--;

		} else {

			drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP;

			drv_data->state = MV64XXX_I2C_STATE_IDLE;

		}

		break;
@@ -184,7 +178,7 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status) 
		}

		drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_SLAVE_DATA;



		if (drv_data->bytes_left == 1)

		if ((drv_data->bytes_left == 1) || drv_data->aborting)

			drv_data->cntl_bits &= ~MV64XXX_I2C_REG_CONTROL_ACK;

		break;
@@ -320,6 +314,7 @@ mv64xxx_i2c_prepare_for_io(struct mv64xxx_i2c_data *drv_data, 
	drv_data->msg = msg;

	drv_data->byte_posn = 0;

	drv_data->bytes_left = msg->len;

	drv_data->aborting = 0;

	drv_data->rc = 0;

	drv_data->cntl_bits = MV64XXX_I2C_REG_CONTROL_ACK |

		MV64XXX_I2C_REG_CONTROL_INTEN | MV64XXX_I2C_REG_CONTROL_TWSIEN;
@@ -359,17 +354,19 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data) 
	}



	if (abort && drv_data->block) {

		drv_data->state = MV64XXX_I2C_STATE_ABORTING;

		drv_data->aborting = 1;

		spin_unlock_irqrestore(&drv_data->lock, flags);



		time_left = wait_event_timeout(drv_data->waitq,

			!drv_data->block,

			msecs_to_jiffies(drv_data->adapter.timeout));



		if (time_left <= 0) {

		if ((time_left <= 0) && drv_data->block) {

			drv_data->state = MV64XXX_I2C_STATE_IDLE;

			dev_err(&drv_data->adapter.dev,

				"mv64xxx: I2C bus locked\n");

				"mv64xxx: I2C bus locked, block: %d, "

				"time_left: %d\n", drv_data->block,

				(int)time_left);

		}

	} else

		spin_unlock_irqrestore(&drv_data->lock, flags);
@@ -510,7 +507,7 @@ mv64xxx_i2c_probe(struct platform_device *pd) 
		goto exit_kfree;

	}



	strncpy(drv_data->adapter.name, MV64XXX_I2C_CTLR_NAME " adapter",

	strlcpy(drv_data->adapter.name, MV64XXX_I2C_CTLR_NAME " adapter",

		I2C_NAME_SIZE);



	init_waitqueue_head(&drv_data->waitq);