[U-Boot] [PATCH 14/24] mxc_i2c: add retries

Troy Kisky
2012-06-22T04:12:09Z

Retry unexpected hardware errors. This
will not retry a received NAK.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
---
drivers/i2c/mxc_i2c.c | 36 +++++++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index df033ea..802f70f 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -213,7 +213,7 @@ void i2c_imx_stop(void)
* Send start signal, chip address and
* write register address
*/
-static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
+static int i2c_init_transfer_(struct mxc_i2c_regs *i2c_regs,
uchar chip, uint addr, int alen)
{
unsigned int temp;
@@ -230,7 +230,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
writeb(0, &i2c_regs->i2sr);
ret = wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
if (ret < 0)
- goto exit;
+ return ret;

/* Start I2C transaction */
temp = readb(&i2c_regs->i2cr);
@@ -239,7 +239,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,

ret = wait_for_sr_state(i2c_regs, ST_BUS_BUSY);
if (ret < 0)
- goto exit;
+ return ret;

temp |= I2CR_MTX | I2CR_TX_NO_AK;
writeb(temp, &i2c_regs->i2cr);
@@ -247,18 +247,36 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
/* write slave address */
ret = tx_byte(i2c_regs, chip << 1);
if (ret < 0)
- goto exit;
+ return ret;

while (alen--) {
ret = tx_byte(i2c_regs, (addr >> (alen * 8)) & 0xff);
if (ret < 0)
- goto exit;
+ return ret;
}
return 0;
-exit:
- i2c_imx_stop();
- /* Disable I2C controller */
- writeb(0, &i2c_regs->i2cr);
+}
+
+static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
+ uchar chip, uint addr, int alen)
+{
+ int retry;
+ int ret;
+ for (retry = 0; retry < 3; retry++) {
+ ret = i2c_init_transfer_(i2c_regs, chip, addr, alen);
+ if (ret >= 0)
+ return ret;
+ i2c_imx_stop(i2c_regs);
+ if (ret == -ENODEV)
+ return ret;
+
+ printf("%s: failed for chip 0x%x retry=%d\n", __func__, chip,
+ retry);
+ if (ret != -ERESTART)
+ writeb(0, &i2c_regs->i2cr); /* Disable controller */
+ udelay(100);
+ }
+ printf("%s: give up i2c_regs=%p\n", __func__, i2c_regs);
return ret;
}

--
1.7.9.5