Re: "I2C_RDWR" ioctl returning EINVAL on Freescale mxc

[Robert Schwebel <r.schwebel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

Alfred,

On Fri, Aug 14, 2009 at 04:09:21PM -0500, alfred steele wrote:
> In my userspace driver for a temp sensor on a i2c bus, i am using the
> /dev interface.  When i use plain read/write syscalls , they seem to
> work just fine. But when i use a combined read/write using the IOCTL
> "I2C_RDWR", i get a return of invalid argument i.e EINVAL from the
> kernel space i2c dev/bus driver.
> 
> int rest  = ioctl(_fd, I2C_RDWR,  trans );
> 
> So basically res gets a value<1 on execution. I am putting in the
> correct slave address. i have double checked on it. What could be the
> other obvious reasons? Could endian ness be an issue as well although
> the userspace is really invisible and if that had been the case i
> would not have got acks from the slave for a i2c scan on the bus.
> i checked the kernel bus driver code for the reason, but cannot figure
> out just by reading the code at this point  as i have a broken h/w.
> iam using the freescale  mxc i2c bus driver on the kernel side.

Can you elaborate:

- which kernel version is that
- which i.MX derivate are you using?

rsc
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