[U-Boot] Odd value for I2C_TIMEOUT in fsl_i2c.c

Wolfgang Denk
2009-09-04T18:28:06Z

Dear Peter Tyser,

In message <1252078092.6005.63.camel@localhost.localdomain> you wrote:
>
> > > Wrong Question. I don't know enough about the I2C protocol. Why is
> > > i2c_wait4bus necessary?
> >
> > Ok, why is it necessary?
>
> Freescale's I2C core supports multiple masters. I'd guess that
> i2c_wait4bus() is used to ensure the bus is not in use by a different
> master before initiating a read or write. Its polling the MBB status
> bit, which is automatically set/cleared when the controller sees a
> START/STOP which supports this.
>
> If this is the case, the timeout should be the maximum (or reasonable
> maximum) time an I2C transaction could take.

Thanks for the explanation - are there actually any boards out there
using more than a single I2C master (i. e. the CPU) on the same I2C
bus?

Best regards,

Wolfgang Denk

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