i2c: uniphier-f: fill TX-FIFO only in IRQ handler for repeated START

- For a repeated START condition, this controller starts data transfer
   immediately after the slave address is written to the TX-FIFO.

 - Once the TX-FIFO empty interrupt is asserted, the controller makes
   a pause even if additional data are written to the TX-FIFO.

Given those circumstances, the data after a repeated START may not be
transferred if the interrupt is asserted while the TX-FIFO is being
filled up. A more reliable way is to append TX data only in the
interrupt handler.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
index fad2b00a8c8cb566233cc04e2e101b62e36124f6..d8a5db14da7964bcc459c16d8dd0659afe16141d 100644 (file)
--- a/drivers/i2c/busses/i2c-uniphier-f.c
+++ b/drivers/i2c/busses/i2c-uniphier-f.c
@@ -269,7 +269,8 @@ handled:
        return IRQ_HANDLED;
 }
 
-static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr)
+static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr,
+                                 bool repeat)
 {
        priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE;
        uniphier_fi2c_set_irqs(priv);
@@ -279,8 +280,12 @@ static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr)
        /* set slave address */
        writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1,
               priv->membase + UNIPHIER_FI2C_DTTX);
-       /* first chunk of data */
-       uniphier_fi2c_fill_txfifo(priv, true);
+       /*
+        * First chunk of data. For a repeated START condition, do not write
+        * data to the TX fifo here to avoid the timing issue.
+        */
+       if (!repeat)
+               uniphier_fi2c_fill_txfifo(priv, true);
 }
 
 static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr)
@@ -361,7 +366,7 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
        if (is_read)
                uniphier_fi2c_rx_init(priv, msg->addr);
        else
-               uniphier_fi2c_tx_init(priv, msg->addr);
+               uniphier_fi2c_tx_init(priv, msg->addr, repeat);
 
        dev_dbg(&adap->dev, "start condition\n");
        /*