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

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Date:   Sun, 24 Apr 2022 05:12:39 +0000
From:   "Usyskin, Alexander" <alexander.usyskin@...el.com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Won Chung <wonchung@...gle.com>,
        "Winkler, Tomas" <tomas.winkler@...el.com>
CC:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Benson Leung <bleung@...omium.org>,
        Prashant Malani <pmalani@...omium.org>,
        "Ceraolo Spurio, Daniele" <daniele.ceraolospurio@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 0/2] thunderbolt: Link USB4 ports to their USB Type-C
 connectors

> > > > 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.
> >
> > Hi Mika,
> >
> > I would prefer the two patches to go to the same tree since it can
> > cause a crash with only the second patch (tbt). Would that sound okay?
> 
> Sounds good to me.

Tomas is MEI maintainer and should ack MEI patch

-- 
Thanks,
Sasha