Commit cc21d0b4 authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang
Browse files

i2c: rcar: init new messages in irq 



Setting up new messages was done in process context while handling a
message was in interrupt context. Because of the HW design, this IP core
is sensitive to timing, so the context switches were too expensive. Move
this setup to interrupt context as well.

In my test setup, this fixed the occasional 'data byte sent twice' issue
which a number of people have seen. It also fixes to send REP_START
after a read message which was wrongly send as a STOP + START sequence
before.

Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent b9d0684c

drivers/i2c/busses/i2c-rcar.c

+43 −47
Original line number Diff line number Diff line
@@ -267,10 +267,17 @@ static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv) 
	rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);

}



static void rcar_i2c_next_msg(struct rcar_i2c_priv *priv)

{

	priv->msg++;

	priv->msgs_left--;

	rcar_i2c_prepare_msg(priv);

}



/*

 *		interrupt functions

 */

static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)

static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)

{

	struct i2c_msg *msg = priv->msg;
@@ -280,7 +287,7 @@ static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr) 
	 * Do nothing

	 */

	if (!(msr & MDE))

		return 0;

		return;



	/*

	 * If address transfer phase finished,
@@ -309,29 +316,23 @@ static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr) 
		 * [ICRXTX] -> [SHIFT] -> [I2C bus]

		 */



		if (priv->flags & ID_LAST_MSG)

		if (priv->flags & ID_LAST_MSG) {

			/*

			 * If current msg is the _LAST_ msg,

			 * prepare stop condition here.

			 * ID_DONE will be set on STOP irq.

			 */

			rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);

		else

			/*

			 * If current msg is _NOT_ last msg,

			 * it doesn't call stop phase.

			 * thus, there is no STOP irq.

			 * return ID_DONE here.

			 */

			return ID_DONE;

		} else {

			rcar_i2c_next_msg(priv);

			return;

		}

	}



	rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_SEND);



	return 0;

}



static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)

static void rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)

{

	struct i2c_msg *msg = priv->msg;
@@ -341,7 +342,7 @@ static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr) 
	 * Do nothing

	 */

	if (!(msr & MDR))

		return 0;

		return;



	if (msr & MAT) {

		/*
@@ -367,9 +368,10 @@ static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr) 
	else

		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);



	if (priv->pos == msg->len && !(priv->flags & ID_LAST_MSG))

		rcar_i2c_next_msg(priv);

	else

		rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_RECV);



	return 0;

}



static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
@@ -462,14 +464,15 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr) 


	/* Stop */

	if (msr & MST) {

		priv->msgs_left--; /* The last message also made it */

		rcar_i2c_flags_set(priv, ID_DONE);

		goto out;

	}



	if (rcar_i2c_is_recv(priv))

		rcar_i2c_flags_set(priv, rcar_i2c_irq_recv(priv, msr));

		rcar_i2c_irq_recv(priv, msr);

	else

		rcar_i2c_flags_set(priv, rcar_i2c_irq_send(priv, msr));

		rcar_i2c_irq_send(priv, msr);



out:

	if (rcar_i2c_flags_has(priv, ID_DONE)) {
@@ -501,35 +504,28 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap, 
		/* This HW can't send STOP after address phase */

		if (msgs[i].len == 0) {

			ret = -EOPNOTSUPP;

			break;

			goto out;

		}

	}



		/* init each data */

		priv->msg = &msgs[i];

		priv->msgs_left = num - i;

	/* init data */

	priv->msg = msgs;

	priv->msgs_left = num;



	rcar_i2c_prepare_msg(priv);



	time_left = wait_event_timeout(priv->wait,

				     rcar_i2c_flags_has(priv, ID_DONE),

					     adap->timeout);

				     num * adap->timeout);

	if (!time_left) {

		rcar_i2c_init(priv);

		ret = -ETIMEDOUT;

			break;

		}



		if (rcar_i2c_flags_has(priv, ID_NACK)) {

	} else if (rcar_i2c_flags_has(priv, ID_NACK)) {

		ret = -ENXIO;

			break;

		}



		if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {

	} else if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {

		ret = -EAGAIN;

			break;

		}



		ret = i + 1; /* The number of transfer */

	} else {

		ret = num - priv->msgs_left; /* The number of transfer */

	}

out:

	pm_runtime_put(dev);

CRA Git | Maintained and supported by SUSTech CRA and CCSE