Re: [PATCH 0/4] Move DP phy switch to PHY driver

[Chris Zhong]

Hi Heiko


On 2017Äę12ÔÂ02ČŐ 05:58, Heiko Stuebner wrote:
> Am Freitag, 1. Dezember 2017, 13:42:46 CET schrieb Doug Anderson:
> > Hi,
> >
> > On Wed, Nov 29, 2017 at 6:27 PM, Chris Zhong <zyw@xxxxxxxxxxxxxx> wrote:
> > > Hi Doug
> > >
> > > Thank you for mentioning this patch.
> > >
> > > I think the focus of the discussion is: can we put the grf control bit to
> > > dts.
> > >
> > > The RK3399 has 2 Type-C phy, but only one DP controller, this "uphy_dp_sel"
> > >
> > > can help to switch these 2 phy. So I think this bit can be considered as a
> > > part of
> > >
> > > Type-C phy, these 2 phy have different bits, just similar to other bits
> > > (such as "pipe-status").
> > >
> > > Put them to DTS file might be a accepted practice.
> > I guess the first step would be finding the person to make a decision.
> > Is that Heiko?  Olof?  Kishon?  Rob?.  As I see it there are a few
> > options:
> >
> > 1. Land this series as-is.  This makes the new bit work just like all
> > the other ones next to it.  If anyone happens to try to use an old
> > device tree on a new kernel they'll break.  Seems rather unlikely
> > given that the whole type C PHY is not really fully functional
> > upstream, but technically this is a no-no from a device tree
> > perspective.
> >
> > 2. Change the series to make this property optional.  If it's not
> > there then the code behaves like it always did.  This would address
> > the "compatibility" problem but likely wouldn't actually help any real
> > people, and it would be extra work.
> >
> > 3. Redo the driver to deprecate all the old offsets / bits and just
> > put the table in the driver, keyed off the compatible string and base
> > address if the IO memory.
> >
> >
> > I can't make this decision.  It's up to those folks who would be
> > landing the patch and I'd be happy with any of them.  What I'm less
> > happy with, however, is the indecision preventing forward progress.
> > We should pick one of the above things and land it.  My own personal
> > bias is #1: just land the series.  No real people will be hurt and
> > it's just adding another property that matches the ones next to it.
> I'd second that #1 . That whole type-c phy thingy never fully worked in
> the past (some for the never used dp output), so personally I don't have
> issues with going that route.
>
>
> >  From a long term perspective (AKA how I'd write the next driver like
> > this) I personally lean towards to "tables in the driver, not in the
> > device tree" but quite honestly I'm happy to take whatever direction
> > the maintainers give.
> It looks like we're in agreement here :-) . GRF stuff should not leak into
> the devicetree, as it causes endless headaches later. But I guess we'll
> need to live with the ones that happened so far.
So, the first step is: move all the private property of tcphy to 
drivers/phy/rockchip/phy-rockchip-typec.c.
Second step: new a member: uphy-dp-sel.
In my mind, we should have discussed these properties before, and then I 
moved them all into DTS.


>

--
Chris Zhong