i2c: add retry-process when slave NACK. [1/1]

PD#SWPL-4761

Problem:
When slave device is busy processing, it is unable to handle the
incoming communication attempts. i2c master have to repeatedly attemp
communication  until the slave sends an ACK after receiving its slave
address.

Solution:
add retry-process when slave NACK.

Verify:
mesonaxg_s420_32_release

Change-Id: Ieb195176cac4b80e223ea6adb502ffd3bc9ef728
Signed-off-by: Daogao Xu <daogao.xu@amlogic.com>

drivers/amlogic/i2c/i2c-meson-master.c

@@ -107,6 +107,7 @@ struct meson_i2c {
 	int			count;
 	int			pos;
 	int			error;
+	int			retries;
 
 	spinlock_t		lock;
 	struct completion	done;
@@ -318,6 +319,8 @@ static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 
 	if (write)
 		meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
+
+	i2c->retries = 0;
 }
 
 static void meson_i2c_stop(struct meson_i2c *i2c)
@@ -340,7 +343,6 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 
 	spin_lock(&i2c->lock);
 
-	meson_i2c_reset_tokens(i2c);
 	ctrl = readl(i2c->regs + REG_CTRL);
 
 	dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
@@ -354,12 +356,15 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 		 * condition.
 		 */
 		dev_dbg(i2c->dev, "error bit set\n");
-		i2c->error = -ENXIO;
-		i2c->state = STATE_IDLE;
-		complete(&i2c->done);
+		if (++i2c->retries >= i2c->adap.retries) {
+			i2c->error = -ENXIO;
+			i2c->state = STATE_IDLE;
+			complete(&i2c->done);
+		}
 		goto out;
 	}
 
+	meson_i2c_reset_tokens(i2c);
 	switch (i2c->state) {
 	case STATE_READ:
 		if (i2c->count > 0) {