On Wed, 2018-02-14 at 17:06 +0200, Jarkko Nikula wrote:
> + José
>
> On 02/13/2018 06:31 PM, Ben Gardner wrote:
> > > Can you test does reverting my guessed commit 2702ea7dbec5 ("i2c:
> > > designware: wait for disable/enable only if necessary") fix it?
> >
> > I verified that reverting 2702ea7dbec5 ("i2c: designware: wait for
> > disable/enable only if necessary") also fixes the issue.
> > Not waiting when disabling the adapter seems perfectly fine. Not
> > waiting when enabling is the problem.
> >
>
> José: There is a regression with above commit and Ben has found a
> fix
> that brings back waiting when enabling the adapter in transfer start:
>
> --- a/drivers/i2c/busses/i2c-designware-master.c
> +++ b/drivers/i2c/busses/i2c-designware-master.c
> @@ -209,7 +209,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev
> *dev)
> i2c_dw_disable_int(dev);
>
> /* Enable the adapter */
> - __i2c_dw_enable(dev, true);
> + __i2c_dw_enable_and_wait(dev, true);
>
> I guess this was just forgotten conversion rather than intentional?
> At
> least commit log is only about skipping waiting at the end of
> transaction.
>
> I'd like to avoid full revert first because of Ben's fix I guess
> still
> keeps the benefit of commit 2702ea7dbec5 and second because of code
> changes revert is also a little bit more labor.
It was intentional as the databook describe the procedure(read
IC_ENABLE_STATUS) to disable but there is no mention of something for
enable however I agree that wait makes sense when enabling too.
>
> > > For linux-stable it is good info to know exactly the commit
> > > causing
> > > regression and mark that in your changelog. It allows linux-
> > > stable folks to
> > > apply fix to earlier kernels and know versions this fix will
> > > still apply if
> > > cannot apply where regression was introduced. Fox example:
> > >
> > > Fixes: commit 2702ea7dbec5 ("i2c: designware: wait for
> > > disable/enable only
> > > if necessary")
> > > Cc: linux-stable <stable@xxxxxxxxxxxxxxx> # 4.13+
> >
> > Do you want me to resubmit this patch with the above lines (Fixes
> > and
> > Cc) added or are you willing to add the appropriate lines and take
> > care of it?
> > I suppose the commit message could use some rewording, now that the
> > issue seems a bit clearer.
> >
>
> Yes please. It always good idea to make busy maintainers' life a bit
> more easier :-)
>
