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: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 6e459a3..36c7930 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -266,6 +266,13 @@
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
*/
@@ -308,21 +315,17 @@
* [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 0;
+ }
}
rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_SEND);
@@ -366,7 +369,10 @@
else
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
- rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_RECV);
+ 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;
}
@@ -461,6 +467,7 @@
/* Stop */
if (msr & MST) {
+ priv->msgs_left--; /* The last message also made it */
rcar_i2c_flags_set(priv, ID_DONE);
goto out;
}
@@ -500,35 +507,28 @@
/* 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);
+ rcar_i2c_prepare_msg(priv);
- time_left = wait_event_timeout(priv->wait,
- rcar_i2c_flags_has(priv, ID_DONE),
- adap->timeout);
- if (!time_left) {
- rcar_i2c_init(priv);
- ret = -ETIMEDOUT;
- break;
- }
-
- if (rcar_i2c_flags_has(priv, ID_NACK)) {
- ret = -ENXIO;
- break;
- }
-
- if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
- ret = -EAGAIN;
- break;
- }
-
- ret = i + 1; /* The number of transfer */
+ time_left = wait_event_timeout(priv->wait,
+ rcar_i2c_flags_has(priv, ID_DONE),
+ num * adap->timeout);
+ if (!time_left) {
+ rcar_i2c_init(priv);
+ ret = -ETIMEDOUT;
+ } else if (rcar_i2c_flags_has(priv, ID_NACK)) {
+ ret = -ENXIO;
+ } else if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
+ ret = -EAGAIN;
+ } else {
+ ret = num - priv->msgs_left; /* The number of transfer */
}
out:
pm_runtime_put(dev);