Re: [PATCH] i2c-mpc: Correct I2C reset procedure

[Joakim Tjernlund <Joakim.Tjernlund@infinera.com>]

On Thu, 2017-05-11 at 13:28 +0200, Wolfram Sang wrote:
> On Tue, May 09, 2017 at 02:03:51PM +0200, Joakim Tjernlund wrote:
> > Current I2C reset procedure is broken in two ways:
> > 1) It only generate 1 START instead of 9 STARTs and STOP.
> > 2) It leaves the bus Busy so every I2C xfer after the first
> >    fixup calls the reset routine again, for every xfer there after.
> > 
> > This fixes both errors. Add an iobarrier_rw() when writing the
> > I2C control register as well to make sure the register reaches the
> > controller in time.
> > 
> > Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
> 
> BTW can this driver be converted to make use of the bus_recovery
> infrastructure?
> 

Maybe, I not familiar with this infrastructure. I did take a look at i2c_generic_recovery()
though and I do not agree with that impl.

The 9 clk's fixup does not cover the the case when an I2C device is stuck write.
To fix stuck in both cases(read or write) you need to generate 9 clk's with a
START in each clk, then a STOP to release the bus.

 Jocke