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

Chris Zhong zyw at rock-chips.com
Sun Dec 3 18:47:08 PST 2017

Hi Heiko

On 2017年12月02日 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 at rock-chips.com> 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 
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

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