Date: Wed, 4 Sep 2024 08:00:13 +0300
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Mario Limonciello <mario.limonciello@amd.com>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>,
	linux-usb@vger.kernel.org, "Rangoju, Raju" <Raju.Rangoju@amd.com>,
	Sanath S <Sanath.S@amd.com>, gregkh@linuxfoundation.org
Subject: Re: [PATCH v2 0/4] Add device links between tunneled USB3 devices
 and USB4 Host
Message-ID: <20240904050013.GZ1532424@black.fi.intel.com>
References: <20240830152630.3943215-1-mathias.nyman@linux.intel.com>
 <321cf204-cf74-4f51-8ed3-8c5738444359@amd.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <321cf204-cf74-4f51-8ed3-8c5738444359@amd.com>

Hi,

On Tue, Sep 03, 2024 at 10:35:00AM -0500, Mario Limonciello wrote:
> On 8/30/2024 10:26, Mathias Nyman wrote:
> > The relationship between a USB4 Host Interface providing USB3 tunnels,
> > and tunneled USB3 devices is not represented in device hierarchy.
> > 
> > This caused issues with power managment as devices may suspend and
> > resume in incorrect order.
> > A device link between the USB4 Host Interface and the USB3 xHCI was
> > originally added to solve this, preventing the USB4 Host Interface from
> > suspending if the USB3 xHCI Host was still active.
> > This unfortunately also prevents USB4 Host Interface from suspending even
> > if the USB3 xHCI Host is only serving native non-tunneled USB devices.
> > 
> > Improve the current powermanagement situation by creating device links
> > directly from tunneled USB3 devices to the USB4 Host Interface they depend
> > on instead of a device link between the hosts.
> > This way USB4 host may suspend when the last tunneled device is
> > disconnected.
> > 
> > Intel xHCI hosts are capable of reporting if connected USB3 devices are
> > tunneled via vendor specific capabilities.
> > Use this until a standard way is available.
> > 
> > v2:
> >   Create device link by default if xHC host is not capable of tunnel
> >   detection but the USB3 ports have tunnel capability reported in ACPI
> >   _DSD object
> > 
> > Mathias Nyman (4):
> >    xhci: Add USB4 tunnel detection for USB3 devices on Intel hosts
> >    usb: Add tunnel_mode parameter to usb device structure
> >    usb: acpi: add device link between tunneled USB3 device and USB4 Host
> >      Interface
> >    thunderbolt: Don't create device link from USB4 Host Interface to USB3
> >      xHC host
> > 
> >   drivers/thunderbolt/acpi.c       | 40 ++++++------------------
> >   drivers/usb/core/usb-acpi.c      | 53 ++++++++++++++++++++++++++++++++
> >   drivers/usb/host/xhci-ext-caps.h |  5 +++
> >   drivers/usb/host/xhci-hub.c      | 36 ++++++++++++++++++++++
> >   drivers/usb/host/xhci.c          | 14 +++++++++
> >   drivers/usb/host/xhci.h          |  3 +-
> >   include/linux/usb.h              |  8 +++++
> >   7 files changed, 128 insertions(+), 31 deletions(-)
> > 
> 
> Hello,
> 
> I had a try with this version of the series but I'm missing a device link
> from XHCI controller after applying it.
> 
> Before series these are the two links (6.11-rc6):
> consumer:pci:0000:00:03.1 ->
> ../../../virtual/devlink/pci:0000:c4:00.5--pci:0000:00:03.1
> consumer:pci:0000:c4:00.3 ->
> ../../../virtual/devlink/pci:0000:c4:00.5--pci:0000:c4:00.3
> 
> After 6.11-rc6 + v2 series only this link:
> consumer:pci:0000:00:03.1 ->
> ../../../virtual/devlink/pci:0000:c4:00.5--pci:0000:00:03.1

Do you have device connected? The link will now be created only when
there is a device router with USB 3.x hub/device connected.