On Mon, Mar 06, 2023 at 03:48:18PM +0100, Benjamin Tissoires wrote:

On Mon, Mar 6, 2023 at 2:07 PM Andy Shevchenko [off-list ref] wrote:

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On Mon, Mar 06, 2023 at 01:36:51PM +0100, Benjamin Tissoires wrote:

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On Mon, Mar 6, 2023 at 11:49 AM Andy Shevchenko [off-list ref] wrote:

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On Thu, Mar 02, 2023 at 06:06:06PM +0100, Benjamin Tissoires wrote:

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On Mar 01 2023, Andy Shevchenko wrote:

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On Tue, Feb 28, 2023 at 01:05:54PM -0600, Daniel Kaehn wrote:

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[1]: https://stackoverflow.com/a/60855157/2511795

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Thanks Andy for your help here, and thanks for that link.

I am trying to test Danny's patch as I want to use it for my HID CI,
being an owner of a CP2112 device myself.

The current setup is using out of the tree patches [2] which are
implementing a platform i2c-hid support and some manual addition of a
I2C-HID device on top of it. This works fine but gets busted every now
and then when the tree sees a change that conflicts with these patches.

So with Danny's series, I thought I could have an SSDT override to
declare that very same device instead of patching my kernel before
testing it.

Of course, it gets tricky because I need to run that under qemu.

I am currently stuck at the "sharing the firmware_node from usb with
HID" step and I'd like to know if you could help me.

On my laptop, if I plug the CP2112 (without using a USB hub), I can get:

$> ls -l /sys/bus/hid/devices/0003:10C4:EA90.*
  lrwxrwxrwx. 1 root root 0 Mar  2 17:02 /sys/bus/hid/devices/0003:10C4:EA90.0079 -> ../../../devices/pci0000:00/0000:00:14.0/usb2/2-9/2-9:1.0/0003:10C4:EA90.0079
$> ls -l /sys/bus/usb/devices/2-9*/firmware_node
  lrwxrwxrwx. 1 root root 0 Mar  2 17:03 /sys/bus/usb/devices/2-9:1.0/firmware_node -> ../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:15/device:16/device:25
  lrwxrwxrwx. 1 root root 0 Mar  2 17:02 /sys/bus/usb/devices/2-9/firmware_node -> ../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:15/device:16/device:25

So AFAIU the USB device is properly assigned a firmware node. My dsdt
also shows the "Device (RHUB)" and I guess everything is fine.

Yes, so far so good.

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However, playing with qemu is not so easy.

I am running qemu with the following arguments (well, almost because I
have a wrapper script on top of it and I also run the compiled kernel
from the current tree):

#> qemu-system-x86_64 -bios /usr/share/edk2/ovmf/OVMF_CODE.fd \
                      -netdev user,id=hostnet0 \
                      -device virtio-net-pci,netdev=hostnet0 \
                      -m 4G \
                      -enable-kvm \
                      -cpu host \
                      -device qemu-xhci -usb \
                      -device 'usb-host,vendorid=0x10c4,productid=0xea90' \
                      -cdrom ~/Downloads/Fedora-Workstation-Live-x86_64-37-1.7.iso

Side question, where can I get those blobs from (EDKII and Fedora Live CD)?
I'm using Debian unstable.

You can install the ovmf package in debian[3], which should have a
similar file.
For the Fedora livecd -> https://getfedora.org/fr/workstation/download/
but any other distribution with a recent enough kernel should show the
same.

Thank you!

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And this is what I get:

#> ls -l /sys/bus/hid/devices/0003:10C4:EA90.*
  lrwxrwxrwx 1 root root 0 Mar  2 16:10 /sys/bus/hid/devices/0003:10C4:EA90.0001 -> ../../../devices/pci0000:00/0000:00:06.0/usb2/2-1/2-1:1.0/0003:10C4:EA90.0001

#> ls -l /sys/bus/usb/devices/2-1*/firmware_node
  ls: cannot access '/sys/bus/usb/devices/2-1*/firmware_node': No such file or directory

Looking at the DSDT, I do not see any reference to the USB hub, so I
wonder if the firmware_node needs to be populated first in the DSDT.

So, where QEMU takes DSDT (ACPI tables in general) from? Can you patch that?
I believe that's the problem in qemu.

That's a good question and it's one I am not sure I have the answer to.
I would have assumed that the DSDT was in the OVMF firmware, but given
that we can arbitrarily add command line arguments, I believe it
probably just provides a baseline and then we are screwed. The OVMF bios
is compiled only once, so I doubt there is any mechanism to
enable/disable a component in the DSDT, or make it dynamically
generated.

We have two ways of filling missing parts:
1) update the original source of DSDT (firmware or bootloader,
   whichever provides that);
2) adding an overlay.

The 2) works _if and only if_ there is *no* existing object in the tables.
In such cases, you can simply provide a *full* hierarchy. See an example of
PCI devices in the kernel documentation on how to do that. I believe something
similar can be done for USB.

Please find attached the dsdt from the Qemu VM.

Thank you!

And after looking at it, your comments below, I think I am understanding
what is happening (on the qemu side at least):

#> grep PCI0.S /sys/bus/acpi/devices/*/path
/sys/bus/acpi/devices/device:02/path:\_SB_.PCI0.S00_
/sys/bus/acpi/devices/device:03/path:\_SB_.PCI0.S10_
/sys/bus/acpi/devices/device:04/path:\_SB_.PCI0.S18_
/sys/bus/acpi/devices/device:05/path:\_SB_.PCI0.S20_
/sys/bus/acpi/devices/device:06/path:\_SB_.PCI0.S28_
/sys/bus/acpi/devices/device:07/path:\_SB_.PCI0.S30_
/sys/bus/acpi/devices/device:08/path:\_SB_.PCI0.S38_
/sys/bus/acpi/devices/device:09/path:\_SB_.PCI0.S40_
/sys/bus/acpi/devices/device:0a/path:\_SB_.PCI0.S48_
/sys/bus/acpi/devices/device:0b/path:\_SB_.PCI0.S50_
/sys/bus/acpi/devices/device:0c/path:\_SB_.PCI0.S58_
/sys/bus/acpi/devices/device:0d/path:\_SB_.PCI0.S60_
/sys/bus/acpi/devices/device:0e/path:\_SB_.PCI0.S68_
/sys/bus/acpi/devices/device:0f/path:\_SB_.PCI0.S70_
/sys/bus/acpi/devices/device:10/path:\_SB_.PCI0.S78_
/sys/bus/acpi/devices/device:11/path:\_SB_.PCI0.S80_
/sys/bus/acpi/devices/device:12/path:\_SB_.PCI0.S88_
/sys/bus/acpi/devices/device:13/path:\_SB_.PCI0.S90_
/sys/bus/acpi/devices/device:14/path:\_SB_.PCI0.S98_
/sys/bus/acpi/devices/device:15/path:\_SB_.PCI0.SA0_
/sys/bus/acpi/devices/device:16/path:\_SB_.PCI0.SA8_
/sys/bus/acpi/devices/device:17/path:\_SB_.PCI0.SB0_
/sys/bus/acpi/devices/device:18/path:\_SB_.PCI0.SB8_
/sys/bus/acpi/devices/device:19/path:\_SB_.PCI0.SC0_
/sys/bus/acpi/devices/device:1a/path:\_SB_.PCI0.SC8_
/sys/bus/acpi/devices/device:1b/path:\_SB_.PCI0.SD0_
/sys/bus/acpi/devices/device:1c/path:\_SB_.PCI0.SD8_
/sys/bus/acpi/devices/device:1d/path:\_SB_.PCI0.SE0_
/sys/bus/acpi/devices/device:1e/path:\_SB_.PCI0.SE8_
/sys/bus/acpi/devices/device:1f/path:\_SB_.PCI0.SF0_
/sys/bus/acpi/devices/device:20/path:\_SB_.PCI0.SF8_

Ah, not much to get out of it.

From DSDT _ADR() you may deduct the PCI BDF of each device in the topology.

And those translate on the DSDT as (for the S30/S38 chunk I am
interested in):

            Device (S30)
            {
                Name (_ADR, 0x00060000)  // _ADR: Address

In PCI this is 00:06.0

                Name (ASUN, 0x06)
                Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
                {
                    Return (PDSM (Arg0, Arg1, Arg2, Arg3, BSEL, ASUN))
                }

                Name (_SUN, 0x06)  // _SUN: Slot User Number
                Method (_EJ0, 1, NotSerialized)  // _EJx: Eject Device, x=0-9
                {
                    PCEJ (BSEL, _SUN)
                }
            }

            Device (S38)
            {
                Name (_ADR, 0x00070000)  // _ADR: Address

00:07.0 respectively.

                Name (ASUN, 0x07)
                Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
                {
                    Return (PDSM (Arg0, Arg1, Arg2, Arg3, BSEL, ASUN))
                }

                Name (_SUN, 0x07)  // _SUN: Slot User Number
                Method (_EJ0, 1, NotSerialized)  // _EJx: Eject Device, x=0-9
                {
                    PCEJ (BSEL, _SUN)
                }
            }

The forwarded USB node is actually on device:07 -> S30_, and as much as
I'd like it to be a regular USB hub, this looks like a virtio node entry
that allows to forward a physical device to the VM.

So IMO, the missing piece might rely on the virtio-usb code which
doesn't export the firmware node, which means I can not extend the
device with an SSDT overlay ATM because the USB node doesn't have the
fw_node.

Ah, that very much may explain this!

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Also note that if I plug the CP2112 over a docking station, I lose the
firmware_node sysfs entries on the host too.

This seems like a lack of firmware node propagating in the USB hub code in
the Linux kernel.

That would make a lot of sense.

FWIW, in the VM I see a firmware node on the pci controller itself:
#> ls -l /sys/devices/pci0000\:00/0000\:00\:06.0/firmware_node
  lrwxrwxrwx 1 root root 0 Mar  6 12:24 /sys/devices/pci0000:00/0000:00:06.0/firmware_node -> ../../LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:07

And one the host, through a USB hub:

#> ls -l /sys/bus/hid/devices/0003:10C4:EA90.*
  lrwxrwxrwx. 1 root root 0 Mar  6 13:26 /sys/bus/hid/devices/0003:10C4:EA90.007C -> ../../../devices/pci0000:00/0000:00:14.0/usb2/2-8/2-8.2/2-8.2.4/2-8.2.4:1.0/0003:10C4:EA90.007C
#> ls -l /sys/bus/usb/devices/2-8*/firmware_node
  lrwxrwxrwx. 1 root root 0 Mar  2 16:53 /sys/bus/usb/devices/2-8:1.0/firmware_node -> ../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:15/device:16/device:1e
  lrwxrwxrwx. 1 root root 0 Mar  2 16:53 /sys/bus/usb/devices/2-8/firmware_node -> ../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:15/device:16/device:1e

Note that the firmware node propagation stopped at 2-8, and 2.8.2 is not
having a firmware node.

It would be nice if you can run `grep -H 15 /sys/bus/acpi/devices/*/status`,

This command (both on the host and on the VM) does not show any USB
device or even the PCI USB controller itself (PNP0A08 or PNP0A03).

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filter out unneeded ones, and for the rest also print their paths:
`cat filtered_list_of_acpi_devs | while read p; do grep -H . $p/path; done`

see above for the VM case, and in the host:

#> grep XHC /sys/bus/acpi/devices/*/path
/sys/bus/acpi/devices/device:15/path:\_SB_.PCI0.XHC_
/sys/bus/acpi/devices/device:16/path:\_SB_.PCI0.XHC_.RHUB
/sys/bus/acpi/devices/device:17/path:\_SB_.PCI0.XHC_.RHUB.HS01
/sys/bus/acpi/devices/device:18/path:\_SB_.PCI0.XHC_.RHUB.HS02
/sys/bus/acpi/devices/device:19/path:\_SB_.PCI0.XHC_.RHUB.HS03
/sys/bus/acpi/devices/device:1a/path:\_SB_.PCI0.XHC_.RHUB.HS04
/sys/bus/acpi/devices/device:1b/path:\_SB_.PCI0.XHC_.RHUB.HS05
/sys/bus/acpi/devices/device:1c/path:\_SB_.PCI0.XHC_.RHUB.HS06
/sys/bus/acpi/devices/device:1d/path:\_SB_.PCI0.XHC_.RHUB.HS07
/sys/bus/acpi/devices/device:1e/path:\_SB_.PCI0.XHC_.RHUB.HS08
/sys/bus/acpi/devices/device:1f/path:\_SB_.PCI0.XHC_.RHUB.SS01
/sys/bus/acpi/devices/device:20/path:\_SB_.PCI0.XHC_.RHUB.SS02
/sys/bus/acpi/devices/device:21/path:\_SB_.PCI0.XHC_.RHUB.SS03
/sys/bus/acpi/devices/device:22/path:\_SB_.PCI0.XHC_.RHUB.SS04
/sys/bus/acpi/devices/device:23/path:\_SB_.PCI0.XHC_.RHUB.SS05
/sys/bus/acpi/devices/device:24/path:\_SB_.PCI0.XHC_.RHUB.SS06
/sys/bus/acpi/devices/device:25/path:\_SB_.PCI0.XHC_.RHUB.HS09
/sys/bus/acpi/devices/device:26/path:\_SB_.PCI0.XHC_.RHUB.HS10
/sys/bus/acpi/devices/device:27/path:\_SB_.PCI0.XHC_.RHUB.USR1
/sys/bus/acpi/devices/device:28/path:\_SB_.PCI0.XHC_.RHUB.USR2
/sys/bus/acpi/devices/device:85/path:\_SB_.PCI0.TXHC
/sys/bus/acpi/devices/device:86/path:\_SB_.PCI0.TXHC.RHUB
/sys/bus/acpi/devices/device:87/path:\_SB_.PCI0.TXHC.RHUB.HS01
/sys/bus/acpi/devices/device:88/path:\_SB_.PCI0.TXHC.RHUB.SS01
/sys/bus/acpi/devices/device:89/path:\_SB_.PCI0.TXHC.RHUB.SS02
/sys/bus/acpi/devices/device:8a/path:\_SB_.PCI0.TXHC.RHUB.SS03
/sys/bus/acpi/devices/device:8b/path:\_SB_.PCI0.TXHC.RHUB.SS04

Which is coherent with the ../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:15/device:16/device:1e
I get when looking at the USB port.

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With this we will see what devices are actually present and up and running
in the system and what their paths in the ACPI namespace.

So it seems that the USB hub functionality is not creating fw_nodes for
its children. But I am not sure this is a battle we want to fight right
now, because it doesn't make a lot of sense IMO to add an SSDT overlay
on a hub.

The description of the attachable devices should really be in the overlays
if user wants them, but it's another story.

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Do you think it would be achievable to emulate that over qemu and use a
mainline kernel without patches?

As long as qemu provides correct DSDT it should work I assume.

Just to be sure I understand, for this to work, we need the DSDT to
export a "Device(RHUB)"?

Not sure I understand the term "export" here. We need a description
of the (to describe) missing parts.

Yes, I meant "to describe" it.

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Or if we fix the USB fw_node propagation, could we just overwrite
"\_SB_.PCI0.S30_"?  "\_SB_.PCI0.S30_" is the name the ACPI is giving to
the USB port in my VM case AFAIU.

I have no idea what is the S30 node.

That gave me the hint I needed, I think. The problem must be in the
virtio drivers, where it doesn't attach the fw_node to the components it
creates. We probably need kind of the same patch Danny is sending in 2/3
in this series, but for virtio.

Sounds like that, indeed.

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[2] https://gitlab.freedesktop.org/bentiss/gitlab-kernel-ci/-/tree/master/VM
[3] https://packages.debian.org/buster/all/ovmf/filelist

-- 
With Best Regards,
Andy Shevchenko