[i2c] i2c_smbus_write_block_data does not send all bytes?!

[Jean Delvare]

Hi Nick,

On Tue, 15 Jul 2008 07:29:56 +0000 (GMT), Nick Teen wrote:
> > You probably want to use i2c_smbus_write_i2c_block_data instead. With
> > i2c_smbus_write_block_data, the first data byte isn't real data,
> > instead in indicates how many bytes follow until the end of the block.
> > It should result in "5D W 11 33 44" in your case though, not sure why
> > you get "5D W 11 03 33" instead.
> 
> i'm aware of the length field and i2c_smbus_write_i2c_block_data doesn't
> work, too. Now i get: 5D W 11 44
> 
> unsigned char values[3];
> int reg = 0x11;
> values[0] = 0x33;
> values[1] = 0x44;
> i2c_smbus_write_i2c_block_data(fd, reg, 2, values);
> 
> If i change the third parameter (length) to 1 I get the 0x33.

Ah, you're in user-space, using i2c-dev? You should have told us so.

> I've no idea! :-(

I don't remember any similar problem, so no idea either. I can only
suspect that your bus driver is doing something wrong. So please give
us the detail of your setup:

* Which version of i2c-dev.h are you using?
* What architecture are you working on?
* Which kernel version are you using?
* What i2c bus driver are you using?
* How do you know for sure what actually goes on the bus?

-- 
Jean Delvare