On 6/22/2012 10:06 AM, Marek Vasut wrote:
Dear Troy Kisky,
Retry unexpected hardware errors. This will not retry a received NAK.
Signed-off-by: Troy Kisky troy.kisky@boundarydevices.com
Why do you need this? Are you getting transmission errors? I think it's because you broke something in the driver, I was getting errors, but managed to hack it together in such a manner, that they didn't happen anymore.
I have an hdmi display that holds the SCL line low for ~3 seconds every ~9 seconds. I added this code while trying to debug that. Granted it is the display's fault, but bus recovery is important.
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;-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; }
Best regards, Marek Vasut