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dm: fsl_i2c: Reword and clarify comment

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Signed-off-by: Mario Six <mario.six@gdsys.cc>
This commit is contained in:
mario.six@gdsys.cc 2016-04-25 08:31:03 +02:00 committed by Heiko Schocher
parent 2b21e96034
commit 386b276918
1 changed files with 6 additions and 14 deletions
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20
drivers/i2c/fsl_i2c.c
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@ -428,22 +428,14 @@ fsl_i2c_read(struct i2c_adapter *adap, u8 chip_addr, uint offset, int olen,
if (i2c_wait4bus(adap) < 0) if (i2c_wait4bus(adap) < 0)
return -1; return -1;
/* To handle the need of I2C devices that require to write few bytes /* Some drivers use offset lengths in excess of 4 bytes. These drivers
* (more than 4 bytes of address as in the case of else part) * adhere to the following convention:
* of data before reading, Negative equivalent of dlen(bytes to write) * - the offset length is passed as negative (that is, the absolute
* is passed, but used the +ve part of len for writing data * value of olen is the actual offset length)
* - the offset itself is passed in data, which is overwritten by the
* subsequent read operation
*/ */
if (olen < 0) { if (olen < 0) {
/* Generate a START and send the Address and
* the Tx Bytes to the slave.
* "START: Address: Write bytes data[len]"
* IF part supports writing any number of bytes in contrast
* to the else part, which supports writing address offset
* of upto 4 bytes only.
* bytes that need to be written are passed in
* "data", which will eventually keep the data READ,
* after writing the len bytes out of it
*/
if (i2c_write_addr(adap, chip_addr, I2C_WRITE_BIT, 0) != 0) if (i2c_write_addr(adap, chip_addr, I2C_WRITE_BIT, 0) != 0)
ret = __i2c_write(adap, data, len); ret = __i2c_write(adap, data, len);