Date:   Fri, 16 Feb 2018 11:44:48 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH 0/12] USB Type-C device-connection, mux and switch support

Hi All.

Ugh, I had my .git/config still setup for sending AHCI patches, so
sorry, please ignore this series while I resend it to the right
people.

Regards,

Hans


On 16-02-18 11:43, Hans de Goede wrote:
> Hi All,
> 
> 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?
> 
> Regards,
> 
> Hans
> 

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