On Wed, Apr 20, 2016 at 11:31:21PM +0200, Wolfram Sang wrote:
> On Mon, Apr 11, 2016 at 05:28:38PM +0200, Jan Glauber wrote:
> > Switch to the i2c bus recovery framework using generic SCL recovery.
> > If this fails try to reset the hardware. The recovery is triggered
> > during START on timeout of the interrupt or failure to reach
> > the START / repeated-START condition.
> >
> > The START function is moved to xfer and while at it:
> > - removed xfer debug message (i2c core already provides debugging)
> > - removed length is zero check
> >
> > Signed-off-by: Jan Glauber <jglauber@xxxxxxxxxx>
> > ---
> > drivers/i2c/busses/i2c-octeon.c | 178 +++++++++++++++++++++++++---------------
> > 1 file changed, 111 insertions(+), 67 deletions(-)
>
> Interesting, it got larger...
>
> >
> > +/**
> > + * octeon_i2c_write_int - read the TWSI_INT register
>
> read_int
OK
> > + int ret, retries = 2;
>
> I don't think 'retries' makes sense here. On failure, you return
> -EAGAIN, so the core will retry 'adapter->retries' times anyhow.
OK. I'll remove the retry looping and call recovery once
if the START condition is not reached. If recovery succeeds
I'll return -EAGAIN, otherwise the error code.
> > - if (length < 1)
> > - return -EINVAL;
>
> So, the adapter support 0-length messages now? Or why was it there? I
> have the feeling this is a seperate patch.
I assumed this check was bogus and there are no valid 0-length
messages...
If 0-length messages can indeed happen I'll keep this check (but why
would the i2c core not check for that in a central place and return
an error before calling xfer() ?).
> > +static void octeon_i2c_prepare_recovery(struct i2c_adapter *adap)
> > +{
> > + struct octeon_i2c *i2c = i2c_get_adapdata(adap);
> > +
> > + /*
> > + * The stop resets the state machine, does not _transmit_ STOP unless
> > + * engine was active.
> > + */
> > + octeon_i2c_stop(i2c);
> > +
> > + octeon_i2c_write_int(i2c, 0);
>
> Maybe a comment why the delay?
Later patch "Flush TWSI writes with readback" adds synchronization after
octeon_i2c_write_int(), so the delays in prepare/unprepare_recovery can
go away.
> > + udelay(5);
> > +}
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