Re: [PATCH v7 4/9] i2c: rk3x: Move setting STATE_START and add STATE_SETUP

[David.Wu]

Hi Doug,

å 2016/5/6 6:56, Doug Anderson åé:
> David,
>
> On Wed, May 4, 2016 at 7:13 AM, David Wu <david.wu@xxxxxxxxxxxxxx> wrote:
> > Signed-off-by: David Wu <david.wu@xxxxxxxxxxxxxx>
> > ---
> > Change in v7:
> > - none
> >
> >   drivers/i2c/busses/i2c-rk3x.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
>
> Probably this change could be dropped now.  Switching the location of
> setting START_START was much more important when you were supporting
> HIGH SPEED mode.  I don't think we need it anymore, right?

Yes, I would drop it next versionïSTATE_SETUP didn't make sense, it was
not much more important, because there was a error printk for 
rk3x_i2c_setup() called failed.

> ...if we want to keep this change, I'd say:
>
> 1. Add a description, like maybe:
>
> To help with debugging add a STATE_SETUP between STATE_IDLE and
> STATE_START to make it more obvious that we're not actually idle but we
> also haven't initiated the start bit.  This change is not expected to
> have any impact but it does delay the changing of state to STATE_START.
> If previously we were getting an erroneous interrupt before we actually
> sent the start bit we'll now be treating that differently.  The new
> behavior (catching the erroneous interrupt) should be better.
>
> 2. Change "i2c->state = STATE_SETUP" to the _start_ of
> rk3x_i2c_setup().  That would have a better chance of catching a
> spurious interrupt.
>
> 3. Add an error check at the start of rk3x_i2c_irq() similar to the
> check for STATE_IDLE (or use the same check and modify the printk).
> Specifically the justification for adding STATE_SETUP is to help with
> debugging (catch interrupts that were unexpected and print more info
> about our state), so we should make it useful for this.
>
>
> -Doug