From cd8843f541cc0ef057e27f1afba46374bbb84219 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Thu, 6 Dec 2018 12:55:26 +0900
Subject: [PATCH] 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>
---
drivers/i2c/busses/i2c-uniphier-f.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
index fad2b00a8c8cb5..d8a5db14da7964 100644
--- 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");
/*
--
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