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mxc_i2c: add retries 

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

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
This commit is contained in:
Troy Kisky 2012-07-19 08:18:16 +00:00 committed by Heiko Schocher
parent d5383a63cd
commit a7f1a00510
1 changed files with 27 additions and 9 deletions
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36
drivers/i2c/mxc_i2c.c
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@ -218,7 +218,7 @@ 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;
@ -235,7 +235,7 @@ 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);
@ -244,7 +244,7 @@ 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);
@ -252,18 +252,36 @@ 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 0;
i2c_imx_stop();
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;
}