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Date: Wed, 20 Apr 2011 20:08:31 +0800
From: wni@...dia.com
To: khali@...ux-fr.org, ben-linux@...ff.org,
lucas.demarchi@...fusion.mobi, ccross@...roid.com,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Wei Ni <wni@...dia.com>
Subject: [PATCH 1/2] i2c: tegra: Retry transfer when unexpected/no_ack status is detected
From: Wei Ni <wni@...dia.com>
Sometimes unexpected status like I2C busy status, Tx FIFO interrupted
and wait on Rx data etc is seen. Add a code to detect such conditions
and return -EAGAIN from driver. This will cause the i2c-core to retry
the transmission as per the retry count and time-out specified by the
platform data of the adapter.
And for no_ack status, also retrun -EAGAIN to retry.
Signed-off-by: Wei Ni <wni@...dia.com>
---
drivers/i2c/busses/i2c-tegra.c | 29 ++++++++++++++++++++++++++---
include/linux/i2c-tegra.h | 2 ++
2 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index b4ab39b..4f5f7f2 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -31,12 +31,15 @@
#include <mach/clk.h>
-#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
-#define BYTES_PER_FIFO_WORD 4
+#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
+#define TEGRA_I2C_RETRIES 3
+#define BYTES_PER_FIFO_WORD 4
#define I2C_CNFG 0x000
#define I2C_CNFG_PACKET_MODE_EN (1<<10)
#define I2C_CNFG_NEW_MASTER_FSM (1<<11)
+#define I2C_STATUS 0x01C
+#define I2C_STATUS_BUSY (1<<8)
#define I2C_SL_CNFG 0x020
#define I2C_SL_CNFG_NEWSL (1<<2)
#define I2C_SL_ADDR1 0x02c
@@ -77,6 +80,7 @@
#define I2C_ERR_NONE 0x00
#define I2C_ERR_NO_ACK 0x01
#define I2C_ERR_ARBITRATION_LOST 0x02
+#define I2C_ERR_UNEXPECTED_STATUS 0x08
#define PACKET_HEADER0_HEADER_SIZE_SHIFT 28
#define PACKET_HEADER0_PACKET_ID_SHIFT 16
@@ -363,6 +367,15 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
goto err;
}
+ if (unlikely((i2c_readl(i2c_dev, I2C_STATUS) & I2C_STATUS_BUSY)
+ && (status == I2C_INT_TX_FIFO_DATA_REQ)
+ && i2c_dev->msg_read
+ && i2c_dev->msg_buf_remaining)) {
+ i2c_dev->msg_err |= I2C_ERR_UNEXPECTED_STATUS;
+ complete(&i2c_dev->msg_complete);
+ goto err;
+ }
+
if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
if (i2c_dev->msg_buf_remaining)
tegra_i2c_empty_rx_fifo(i2c_dev);
@@ -466,9 +479,12 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
if (i2c_dev->msg_err == I2C_ERR_NO_ACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;
- return -EREMOTEIO;
+ return -EAGAIN;
}
+ if (i2c_dev->msg_err & I2C_ERR_UNEXPECTED_STATUS)
+ return -EAGAIN;
+
return -EIO;
}
@@ -598,6 +614,13 @@ static int tegra_i2c_probe(struct platform_device *pdev)
i2c_dev->adapter.algo = &tegra_i2c_algo;
i2c_dev->adapter.dev.parent = &pdev->dev;
i2c_dev->adapter.nr = pdev->id;
+ if (pdata->retries)
+ i2c_dev->adapter.retries = pdata->retries;
+ else
+ i2c_dev->adapter.retries = TEGRA_I2C_RETRIES;
+
+ if (pdata->timeout)
+ i2c_dev->adapter.timeout = pdata->timeout;
ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
if (ret) {
diff --git a/include/linux/i2c-tegra.h b/include/linux/i2c-tegra.h
index 9c85da4..8ee5b37 100644
--- a/include/linux/i2c-tegra.h
+++ b/include/linux/i2c-tegra.h
@@ -20,6 +20,8 @@
struct tegra_i2c_platform_data {
unsigned long bus_clk_rate;
+ int retries;
+ int timeout; /* in jiffies */
};
#endif /* _LINUX_I2C_TEGRA_H */
--
1.7.0
--
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