Re: [PATCH 0/3] extcon: Add Type-C Virtual PD

Hi Rob,

On 9/15/20 8:15 AM, Rob Herring wrote:

On Fri, Sep 04, 2020 at 11:23:21PM +0200, Heiko Stübner wrote:

quoted

Hi Jagan,

Am Freitag, 4. September 2020, 21:18:27 CEST schrieb Jagan Teki:

quoted

USB Type-C protocol supports various modes of operations
includes PD, USB3, and Altmode. If the platform design
supports a Type-C connector then configuring these modes
can be done via enumeration.

However, there are some platforms that design these modes
of operations as separate protocol connectors like design
Display Port from on-chip USB3 controller. So accessing
Type-C Altmode Display Port via onboard Display Port 
connector instead of a Type-C connector.
 
These kinds of platforms require an explicit extcon driver
in order to handle Power Delivery and Port Detection.

This series support this Type-C Virtual PD and enable the
same in ROCK Pi 4C SBC.

Any inputs?

I tend to disagree on the design via an extcon.

I don't accept new extcon bindings or users of it either. It's a 
poorly thought out collection of Linux driver properties. Use the usb 
connector binding.

I agree the prior binding format of extcon with 'extcon' property name
is not proper. So, I'll try to bind new style. But, I have a question.
Do you have the objection of the use of extcon like 'users of it either' 
of your comment?

quoted

That the Rockchip rk3399 currently carries that extcon thingy is unfortunate
and only works for ChromeOS devices based on the rk3399.

The kernel now has a real type-c framework so we should not extend this
extcon hack any further, because that will make it even harder to roll back
later. Also simply because other Rockchip boards currently can't really make
use of type-c due to this, as they use the fsusb302 phys directly connected.

ChromeOS actually spend some time to make the cros-ec pd part of the type-c
framework if I remember correctly, so a viable battle plan would be to:

(1) move the Rockchip type-c phy driver to actually be part of the type-c
    framework, with the extcon being a deprecated fallback for old DTs.
(2) implement your gpio-altmode as part of the type-c framework
    (which may even already exist)


In short, please don't extend the rk3399 type-c extcon hack.

Thanks
Heiko

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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