[PATCH v2 1/2] serial: ns16550: Revert "Move PCI access from ofdata_to_platdata() to probe()"

[Andy Shevchenko]

+Cc: Chee Hong

On Thu, Apr 2, 2020 at 10:09 PM Andy Shevchenko
<andy.shevchenko at gmail.com> wrote:
>
> On Thu, Apr 2, 2020 at 7:55 AM Bin Meng <bmeng.cn at gmail.com> wrote:
> > On Thu, Apr 2, 2020 at 1:55 AM Simon Glass <sjg at chromium.org> wrote:
> > > On Wed, 1 Apr 2020 at 11:39, Andy Shevchenko <andy.shevchenko at gmail.com> wrote:
> > > > On Wed, Apr 01, 2020 at 10:56:26AM -0600, Simon Glass wrote:
> > > > > On Wed, 1 Apr 2020 at 08:45, Andy Shevchenko <andy.shevchenko at gmail.com> wrote:
> > > > > > On Wed, Apr 1, 2020 at 5:32 PM Bin Meng <bmeng.cn at gmail.com> wrote:
> > > > > > > On Wed, Apr 1, 2020 at 9:58 PM Andy Shevchenko
> > > > > > > <andriy.shevchenko at linux.intel.com> wrote:
> > > > > > > >
> > > > > > > > The commit breaks serial console on the Intel Edison.
> > > > > > > >
> > > > > > > > This reverts commit 720f9e1fdb0c92d3fd16e1bfc25bcbd35612675c.
> > > > > > > >
> > > > > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> > > > > > > > ---
> > > > > > > >  drivers/serial/ns16550.c | 40 ++++++++++++----------------------------
> > > > > > > >  1 file changed, 12 insertions(+), 28 deletions(-)
> > > > > > > >
> > > > > > >
> > > > > > > Could you please spend some time to investigate why this breaks Intel Edison?
> > > > > > >
> > > > > > > Reverting this patch would mean we break other boards too as
> > > > > > > Wolfgang's patch wanted to fix the breakage in the first place. Much
> > > > > > > appreciated!
> > > > > >
> > > > > > I guess I'm wrong person here. The DM code is a complete black box to me.
> > > > > > Nevertheless, I may test any provided fix / debug / etc patch by request.
> > > > > >
> > > > > > And I think it's fair to investigate by the one who made a regression
> > > > > > in the first place.
> > > > >
> > > > > Given that we have conflicting breakages, we need to debug Edison.
> > > >
> > > > I would glad to test any suggested change or debug patch!
> > > >
> > > > > Does it enable the debug UART?
> > > >
> > > > If I am not mistaken, it does not.
> > >
> > > Looks like you are right. If you know the address you could do that -
> > > see minnowmax for an example.
> >
> > Please suggest what's the best approach to proceed.
>
> I think I understand what happened, and Wolfgang's patch *is* a culprit.
>
> In serial_intel_mid.c we setup a divisor before probing the actual
> device. Now, since the address retrieving has been moved further in
> the initialization, we are writing to unknown registers and thus don't
> properly initialize hardware.
>
> So, the proper fix would be in my opinion to introduce a call back or
> some other way to make ordering possible, like registering hw_init
> callback in probe which will be called in the ns16550, or even do this
> as a callback for all serial class drivers.
>
> I don't dare to dive into this anticipating that crap will hit the fan.
> So, please, who is knowing serial code, fix this asap!
>
> --
> With Best Regards,
> Andy Shevchenko



-- 
With Best Regards,
Andy Shevchenko