linux-kernel - Re: [PATCH 0/2] thunderbolt: Link USB4 ports to their USB Type-C connectors

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Message-ID: <Yl/l7gjRXj41a93q@lahna>
Date:   Wed, 20 Apr 2022 13:52:30 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Won Chung <wonchung@...gle.com>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Alexander Usyskin <alexander.usyskin@...el.com>,
        Benson Leung <bleung@...omium.org>,
        Prashant Malani <pmalani@...omium.org>,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] thunderbolt: Link USB4 ports to their USB Type-C
 connectors

Hi,

On Mon, Apr 18, 2022 at 05:59:30PM +0000, Won Chung wrote:
> Currently, USB port is linked to Type C connector, using the component
> framework, if they share the same _PLD fields from ACPI table. Type C
> port-mapper searches for devices with the same _PLD values, and
> aggregate them as components.
> 
> When there is another device that share the same _PLD but does not
> registers a component, Type C connector (component master) would never
> be bound due to a component match entry device without a component
> registered. There exists some cases where USB4 port also shares the same
> _PLD with USB port and Type C connector, so we need to register a
> component for USB4 ports too, linking USB4 port with Type C connector.
> Otherwise, link between USB port and Type C connector would not
> work either.
> 
> Due to the nature of the component framework, all registered components
> are shared by all component match despite the relevance. MEI subsystems
> also use the component framework to bind to i915 driver, which try to
> match components registered by USB ports and USB4 ports. This can be
> problematic since MEI assumes that there is a driver bound to the
> component device, while USB4 port does not bind to any drivers. MEI's
> component match callback functions should handle such case to avoid NULL
> pointer dereference when USB4 port registers a component.
> 
> In summary this patch series
> 1. Fixes MEI subsystem's component match callbacks to handle a component
> device without any driver bound
> 2. Registers a component for USB4 ports to link them to Type C
> connectors, similar to USB ports.
> 
> Heikki Krogerus (1):
>   thunderbolt: Link USB4 ports to their USB Type-C connectors
> 
> Won Chung (1):
>   misc/mei: Add NULL check to component match callback functions

The Thunderbolt patch looks good to me. Do you want me to take the both
patches through the Thunderbolt tree or they can go separately? I need
an ack from the mei maintainer it goes through my tree.