Re: [REGRESSION] usb: acpi: add device link between tunneled USB3 device and USB4 Host Interface

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Thu, Oct 03, 2024 at 08:42:21AM -0500, Mario Limonciello wrote:
> On 10/3/2024 08:27, Mika Westerberg wrote:
> > On Thu, Oct 03, 2024 at 08:10:11AM -0500, Mario Limonciello wrote:
> > > On 10/3/2024 00:47, Mika Westerberg wrote:
> > > > Hi Harry,
> > > > 
> > > > On Wed, Oct 02, 2024 at 01:42:29PM -0400, Harry Wentland wrote:
> > > > > I was checking out the 6.12 rc1 (through drm-next) kernel and found
> > > > > my system hung at boot. No meaningful message showed on the kernel
> > > > > boot screen.
> > > > > 
> > > > > A bisect revealed the culprit to be
> > > > > 
> > > > > commit f1bfb4a6fed64de1771b43a76631942279851744 (HEAD)
> > > > > Author: Mathias Nyman <mathias.nyman@linux.intel.com>
> > > > > Date:   Fri Aug 30 18:26:29 2024 +0300
> > > > > 
> > > > >       usb: acpi: add device link between tunneled USB3 device and USB4 Host Interface
> > > > > 
> > > > > A revert of this single patch "fixes" the issue and I can boot again.
> > > > > The system in question is a Thinkpad T14 with a Ryzen 7 PRO 6850U CPU.
> > > > > It's running Arch Linux but I doubt that's of consequence.
> > > > > 
> > > > > lspci output:
> > > > >       https://gist.github.com/hwentland/59aef63d9b742b7b64d2604aae9792e0
> > > > > acpidump:
> > > > >       https://gist.github.com/hwentland/4824afc8d712c3d600be5c291f7f1089
> > > > > 
> > > > > Mario suggested I try modprobe.blacklist=xhci-hcd but that did nothing.
> > > > > Another suggestion to do usbcore.nousb lets me boot to the desktop
> > > > > on a kernel with the faulty patch, without USB functionality, obviously.
> > > > > 
> > > > > I'd be happy to try any patches, provide more data, or run experiments.
> > > > 
> > > > Do you boot with any device connected?
> > > > > Second thing that I noticed, though I'm not familiar with AMD hardware,
> > > > but from your lspci dump, I do not see the PCIe ports that are being
> > > > used to tunnel PCIe. Does this system have PCIe tunneling disabled
> > > > somehow?
> > > 
> > > On some OEM systems it's possible to lock down from BIOS to turn off PCIe
> > > tunneling, and I agree that looks like the most common cause.
> > > 
> > > This is what you would see on a system that has tunnels (I checked on my
> > > side w/ Z series laptop w/ Rembrandt and a dock connected):
> > > 
> > >             +-03.0
> > >             +-03.1-[03-32]--
> > >             +-04.0
> > >             +-04.1-[33-62]----00.0-[34-62]--+-02.0-[35]----00.0
> > >             |                               \-04.0-[36-62]--
> > > 
> > > 00:03.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Family
> > > 17h-19h PCIe Dummy Host Bridge [1022:14b7] (rev 01)
> > > 00:03.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Family 19h
> > > USB4/Thunderbolt PCIe tunnel [1022:14cd]
> > > 00:04.0 Host bridge [0600]: Advanced Micro Devices, Inc. [AMD] Family
> > > 17h-19h PCIe Dummy Host Bridge [1022:14b7] (rev 01)
> > > 00:04.1 PCI bridge [0604]: Advanced Micro Devices, Inc. [AMD] Family 19h
> > > USB4/Thunderbolt PCIe tunnel [1022:14cd]
> > 
> > Okay this is more like what I expected, although probably not the
> > reason here.
> > 
> > Are you able to replicate the issue if you disable PCIe tunneling from
> > the BIOS on your reference system? (Probably not but just in case).
> 
> I checked on the Lenovo Z13 laptop I have and turned off "USB port" in BIOS
> setup and this caused the endpoints 3.1 and 4.1 I listed above to disappear
> but the system still boots up just fine for me on 6.12-rc1.

Okay thanks for checking!

> > > > You don't see anything on the console? It's all blank or it just hangs
> > > > after some messages?
> > > 
> > > I guess it is getting stuck on fwnode_find_reference() because it never
> > > finds the given node?
> > 
> > Looking at the code, I don't see where it could get stuck. If for some
> > reason there is no such reference (there is based on the ACPI dump) then
> > it should not affect the boot. It only matters when power management is
> > involved.
> 
> Nothing jumps out to me either.  Maybe this is a situation that Harry can
> sprinkle a bunch of printk's all over usb_acpi_add_usb4_devlink() to
> enlighten what's going on (assuming the console output is "working" when
> this happened).

There are couple of places there that may cause it to crash, I think.
And the __free() magic is something I cannot wrap my head around :(

Anyways, Harry can you try the below patch and see if it makes any
difference? Also if it does please provide dmesg.

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
index 21585ed89ef8..90360f7ca905 100644
--- a/drivers/usb/core/usb-acpi.c
+++ b/drivers/usb/core/usb-acpi.c
@@ -157,6 +157,7 @@ EXPORT_SYMBOL_GPL(usb_acpi_set_power_state);
  */
 static int usb_acpi_add_usb4_devlink(struct usb_device *udev)
 {
+	struct fwnode_handle *nhi_fwnode;
 	const struct device_link *link;
 	struct usb_port *port_dev;
 	struct usb_hub *hub;
@@ -165,11 +166,12 @@ static int usb_acpi_add_usb4_devlink(struct usb_device *udev)
 		return 0;
 
 	hub = usb_hub_to_struct_hub(udev->parent);
-	port_dev = hub->ports[udev->portnum - 1];
+	if (WARN_ON(!hub))
+		return 0;
 
-	struct fwnode_handle *nhi_fwnode __free(fwnode_handle) =
-		fwnode_find_reference(dev_fwnode(&port_dev->dev), "usb4-host-interface", 0);
+	port_dev = hub->ports[udev->portnum - 1];
 
+	nhi_fwnode = fwnode_find_reference(dev_fwnode(&port_dev->dev), "usb4-host-interface", 0);
 	if (IS_ERR(nhi_fwnode))
 		return 0;
 
@@ -180,12 +182,14 @@ static int usb_acpi_add_usb4_devlink(struct usb_device *udev)
 	if (!link) {
 		dev_err(&port_dev->dev, "Failed to created device link from %s to %s\n",
 			dev_name(&port_dev->child->dev), dev_name(nhi_fwnode->dev));
+		fwnode_handle_put(nhi_fwnode);
 		return -EINVAL;
 	}
 
-	dev_dbg(&port_dev->dev, "Created device link from %s to %s\n",
-		dev_name(&port_dev->child->dev), dev_name(nhi_fwnode->dev));
+	dev_info(&port_dev->dev, "Created device link from %s to %s\n",
+		 dev_name(&port_dev->child->dev), dev_name(nhi_fwnode->dev));
 
+	fwnode_handle_put(nhi_fwnode);
 	return 0;
 }