linux-kernel - Re: [PATCH v3 00/12] USB Type-C device-connection, mux and switch support

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Date:   Mon, 26 Feb 2018 12:19:52 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v3 00/12] USB Type-C device-connection, mux and switch
 support

Hi,

On 26-02-18 11:59, Andy Shevchenko wrote:
> On Mon, Feb 26, 2018 at 11:09 AM, Hans de Goede <hdegoede@...hat.com> wrote:
>> Hi All,
>>
>> Here is version 3 of Heikki's and my USB Type-C device-connection, mux and
>> switch support series. Version 2 and 3 bring various small code and style
>> fixes based on review (no major changes).
>>
>> Here is the original cover-letter of v1:
>>
>> Some devices with an USB Type-C connector have a bunch of muxes
>> behind that connector which need to be controlled by the kernel (rather
>> then having them controlled by firmware as on most devices).
>>
>> Quite a while back I submitted a patch-series to tie together these muxes
>> and the Type-C Port Manager (tcpm) code, using the then new drivers/mux
>> framework. But the way I used the mux framework went against what it was
>> designed for, so in the end that series got nowhere.
>>
>> Heikki Krogerus from Intel, who maintains the USB TYPEC subsystem, has
>> recently been working on solving the same problem for some boards he is
>> doing hardware-enablement for.
>>
>> Heikki has come up with a number of infrastructure patches for this.
>> The first one is a new device-connection framework. This solves the
>> problem of describing non bus device-links on x86 in what in my experience
>> with this problematic area is a really nice simple, clean and *generic*
>> way. This could for example in the near future also replace the custom
>> lookup code in the pwm subsys and the custom pwm_add_table() /
>> pwm_remove_table() functions.
>>
>> The other 3 patches add a framework for the different type of Type-C /
>> USB "muxes".
>>
>> Heikki and I have gone through a number of iterations of these patches
>> together and we believe these are now ready for merging. Since merging
>> infrastructure patches without users is not done and Heikki's own use-case
>> for these is not yet ready for merging, the rest of this series consists
>> of patches by me to make the Type-C connector found on some Cherry Trail
>> devices (finally) be able to actually work as an USB port and not just
>> a charge port.
>>
>> The last patch uses the new usb-role-switch framework to also do proper
>> devcie / host switching on CHT devices with a USB micro AB connector.
>> This is also a big feature for CHT users, because before this they had
>> to do a reboot to get an OTG-host cable recognized (on some devices).
>>
>> Part of this series is an usb-role-switch driver for the role-switch
>> found inside the xhci controller on e.g. CHT devices, this is currently
>> implemented as the generic xhci controller instantiating a platform
>> child-device for this, since this really is a separate chunk of HW
>> which happens to sit in the XHCI mmio space. This approach may not be
>> universally liked, given that in this new series the role-switch driver
>> is much smaller and does not have any external deps anymore we could
>> just integrate it into the xhci code if that is preferred.
>>
>> About merging this series (once everything is reviewed, etc.), there are
>> quite some interdependencies in it esp. a lot of the patches depend on
>> the first patch. Luckily patches 1-10 all apply to subsystems which are
>> maintained by Greg (most to the USB subsys). Which just leaves patches
>> 11 and 12 once 1-10 are merged. Greg, can you create an immutable branch
>> for the platform/x86 and extcon maintainers to merge once this is done?
> 
> Didn't have time to comment on v2, so here we are:
> you are using in even the same file two styles, i.e. IS_ERR_OR_NULL
> vs. !x || IS_ERR(x) (and negative ones).

Good catch, I only see this in "usb: common: Small class for USB role switches",
will fix for v4.

> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

So with the above fixed I can apply your reviewed-by to the entire series?

Regards,

Hans