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V4L/DVB (6857): cx23885: correctly join I2C writes and reads from same address

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When an I2C message specifies a write then a read from the same I2C address,
we need to tell the chip to not release the bus between the message parts.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Chris Pascoe 2007-12-15 03:31:09 -03:00 committed by Mauro Carvalho Chehab
parent bc51471088
commit 5e3c5967da
1 changed files with 39 additions and 14 deletions
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53
drivers/media/video/cx23885/cx23885-i2c.c
View file

@ -37,8 +37,10 @@ static unsigned int i2c_scan = 0;
module_param(i2c_scan, int, 0444);
MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");
#define dprintk(level,fmt, arg...) if (i2c_debug >= level) \
printk(KERN_DEBUG "%s: " fmt, dev->name , ## arg)
#define dprintk(level, fmt, arg...) do { \
if (i2c_debug >= level) \
printk(KERN_DEBUG "%s: " fmt, dev->name , ## arg); \
} while (0)
#define I2C_WAIT_DELAY 32
#define I2C_WAIT_RETRY 64
@ -77,14 +79,18 @@ static int i2c_wait_done(struct i2c_adapter *i2c_adap)
}
static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
const struct i2c_msg *msg, int last)
const struct i2c_msg *msg, int joined_rlen)
{
struct cx23885_i2c *bus = i2c_adap->algo_data;
struct cx23885_dev *dev = bus->dev;
u32 wdata, addr, ctrl;
int retval, cnt;
dprintk(1, "%s(msg->len=%d, last=%d)\n", __FUNCTION__, msg->len, last);
if (joined_rlen)
dprintk(1, "%s(msg->wlen=%d, nextmsg->rlen=%d)\n", __FUNCTION__,
msg->len, joined_rlen);
else
dprintk(1, "%s(msg->len=%d)\n", __FUNCTION__, msg->len);
/* Deal with i2c probe functions with zero payload */
if (msg->len == 0) {
@ -107,6 +113,8 @@ static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
if (msg->len > 1)
ctrl |= I2C_NOSTOP | I2C_EXTEND;
else if (joined_rlen)
ctrl |= I2C_NOSTOP;
cx_write(bus->reg_addr, addr);
cx_write(bus->reg_wdata, wdata);
@ -130,6 +138,8 @@ static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
if (cnt < msg->len - 1)
ctrl |= I2C_NOSTOP | I2C_EXTEND;
else if (joined_rlen)
ctrl |= I2C_NOSTOP;
cx_write(bus->reg_addr, addr);
cx_write(bus->reg_wdata, wdata);
@ -151,19 +161,22 @@ static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
eio:
retval = -EIO;
err:
printk(" ERR: %d\n", retval);
if (i2c_debug)
printk(" ERR: %d\n", retval);
return retval;
}
static int i2c_readbytes(struct i2c_adapter *i2c_adap,
const struct i2c_msg *msg, int last)
const struct i2c_msg *msg, int joined)
{
struct cx23885_i2c *bus = i2c_adap->algo_data;
struct cx23885_dev *dev = bus->dev;
u32 ctrl, cnt;
int retval;
dprintk(1, "%s(msg->len=%d, last=%d)\n", __FUNCTION__, msg->len, last);
if (i2c_debug && !joined)
dprintk(1, "%s(msg->len=%d)\n", __FUNCTION__, msg->len);
/* Deal with i2c probe functions with zero payload */
if (msg->len == 0) {
@ -179,8 +192,12 @@ static int i2c_readbytes(struct i2c_adapter *i2c_adap,
return 0;
}
if (i2c_debug)
printk(" <R %02x", (msg->addr << 1) + 1);
if (i2c_debug) {
if (joined)
printk(" R");
else
printk(" <R %02x", (msg->addr << 1) + 1);
}
for(cnt = 0; cnt < msg->len; cnt++) {
@ -209,7 +226,8 @@ static int i2c_readbytes(struct i2c_adapter *i2c_adap,
eio:
retval = -EIO;
err:
printk(" ERR: %d\n", retval);
if (i2c_debug)
printk(" ERR: %d\n", retval);
return retval;
}
@ -227,15 +245,22 @@ static int i2c_xfer(struct i2c_adapter *i2c_adap,
__FUNCTION__, num, msgs[i].addr, msgs[i].len);
if (msgs[i].flags & I2C_M_RD) {
/* read */
retval = i2c_readbytes(i2c_adap, &msgs[i], i+1 == num);
retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
} else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
msgs[i].addr == msgs[i + 1].addr) {
/* write then read from same address */
retval = i2c_sendbytes(i2c_adap, &msgs[i],
msgs[i + 1].len);
if (retval < 0)
goto err;
i++;
retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
} else {
/* write */
retval = i2c_sendbytes(i2c_adap, &msgs[i], i+1 == num);
if (retval < 0)
goto err;
retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
}
if (retval < 0)
goto err;
}
return num;