Hi,
I've been having a go at using a device-tree i2c-mux driver via the ACPI "PRP0001" compatibility layer.
I'm running Linux 5.15.62.
I've written an SSDT overlay, and when I load it, everything seems to work fine.
The mux channels show up and are usable to access devices that are connected to the mux channels.
When I remove the overlay however, the operation appears to succeed, but I get a warning and stack trace output from the kernel:
[root@awplus overlays]# mkdir /sys/kernel/config/acpi/table/bay_1_mux
[root@awplus overlays]# cat mux_only.aml > /sys/kernel/config/acpi/table/bay_1_mux/aml
[root@awplus overlays]# ls /sys/bus/i2c/devices
i2c-0 i2c-12 i2c-4 i2c-8
i2c-1 i2c-13 i2c-5 i2c-9
i2c-10 i2c-2 i2c-6 i2c-PRP0001:00
i2c-11 i2c-3 i2c-7
[root@awplus overlays]# rmdir /sys/kernel/config/acpi/table/bay_1_mux
[ 92.682779] ------------[ cut here ]------------
[root@awplus ove[ 92.687417] kernfs: can not remove 'physical_node', no directory
rlays]# [ 92.694902] WARNING: CPU: 7 PID: 83 at fs/kernfs/dir.c:1542 kernfs_remove_by_name_ns+0x82/0x90
[ 92.704086] Modules linked in: mvIntDrv(O) xt_nat xt_mark xt_addrtype xt_MASQUERADE xt_LOG pluggable(O) nf_log_syslog iptable_nat efivarfs diag tipc idprom_i2c(O) epi3_boardinfo_i2c(O) psuslot_epi3_register(O) psuslot_gpio_group(O) psuslot(O) gpiopins_boardinfo(O) SBx90xGEN3(O) idprom(O) epi3_boardinfo(O) boardinfo(O)
[ 92.732146] CPU: 7 PID: 83 Comm: kworker/u128:1 Tainted: G O 5.15.63 #2
[ 92.740071] Hardware name: congatec AG conga-B7E3/conga-B7E3, BIOS 5.13 08/23/2021
[ 92.747636] Workqueue: kacpi_hotplug acpi_device_del_work_fn
[ 92.753301] RIP: 0010:kernfs_remove_by_name_ns+0x82/0x90
[ 92.758629] Code: c0 5d 41 5c 41 5d e9 dd 21 b6 00 48 c7 c7 20 59 b6 bc e8 31 6d e1 ff b8 fe ff ff ff eb e3 48 c7 c7 28 9c 7d bc e8 f0 52 73 00 <0f> 0b b8 fe ff ff ff eb ce 0f 1f 44 00 00 41 57 41 56 41 55 41 54
[ 92.777332] RSP: 0018:ffffae03c04e7b68 EFLAGS: 00010286
[ 92.782571] RAX: 0000000000000000 RBX: ffff979c47324bd0 RCX: 0000000000000000
[ 92.789704] RDX: ffff97a34e3e6490 RSI: ffff97a34e3db450 RDI: ffff97a34e3db450
[ 92.796836] RBP: ffff979c4a909e40 R08: ffff97a36f2eaba8 R09: 00000000ffffbfff
[ 92.803965] R10: ffff97a34e0a0000 R11: ffff97a34e0a0000 R12: ffffae03c04e7b88
[ 92.811097] R13: ffff979c47320a88 R14: ffff979c47320d80 R15: ffffae03c04e7b88
[ 92.818239] FS: 0000000000000000(0000) GS:ffff97a34e3c0000(0000) knlGS:0000000000000000
[ 92.826321] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 92.832070] CR2: 00007faeda657010 CR3: 000000010788c000 CR4: 00000000003506e0
[ 92.839216] Call Trace:
[ 92.841688] <TASK>
[ 92.843822] acpi_unbind_one+0xec/0x170
[ 92.847672] device_del+0x1a3/0x4b0
[ 92.851189] ? kernfs_name_hash+0xd/0x80
[ 92.855129] ? recalibrate_cpu_khz+0x10/0x10
[ 92.859425] ? ktime_get_mono_fast_ns+0x49/0x90
[ 92.863972] device_unregister+0x9/0x20
[ 92.867823] i2c_del_adapter.part.0+0x1bf/0x250
[ 92.872383] i2c_mux_del_adapters+0x81/0xc0
[ 92.876576] pca954x_remove+0x20/0x30
[ 92.880269] i2c_device_remove+0x1a/0x80
[ 92.884206] __device_release_driver+0x179/0x250
[ 92.888848] device_release_driver+0x1f/0x30
[ 92.893126] bus_remove_device+0xcd/0x110
[ 92.897152] device_del+0x18b/0x4b0
[ 92.900666] ? device_match_fwnode+0x20/0x20
[ 92.904964] device_unregister+0x9/0x20
[ 92.908817] i2c_acpi_notify+0x115/0x150
[ 92.912771] ? device_del+0x2e1/0x4b0
[ 92.916446] blocking_notifier_call_chain+0x58/0x80
[ 92.921351] acpi_device_del_work_fn+0x78/0xc0
[ 92.925809] process_one_work+0x1d8/0x370
[ 92.929848] worker_thread+0x48/0x3d0
[ 92.933525] ? rescuer_thread+0x380/0x380
[ 92.937562] kthread+0x122/0x140
[ 92.940805] ? set_kthread_struct+0x40/0x40
[ 92.945017] ret_from_fork+0x22/0x30
[ 92.948610] </TASK>
[ 92.950828] ---[ end trace 76fd3a73e923dd51 ]---
[root@awplus overlays]# ls /sys/bus/i2c/devices
i2c-0 i2c-1 i2c-2 i2c-3 i2c-4 i2c-5
I have included the source code for my SSDT overlay below.
Is there something that I am doing incorrectly?
Or, is there some missing support around removing ACPI overlays that use device-tree drivers?
Thank you for your time,
Joshua Scott
DefinitionBlock ("mux_only.aml", "SSDT", 1, "ATL", "TEST", 0x00000001)
{
External (\_SB.I2CA, DeviceObj)
Scope (\_SB.I2CA)
{
// 8-Channel i2c mux
Device (MUX0)
{
Name (_HID, "PRP0001")
Name (_CRS, ResourceTemplate () {
I2cSerialBusV2 (0x74, ControllerInitiated,
400000, AddressingMode7Bit,
"\\_SB.I2CA", 0x00,
ResourceConsumer, , Exclusive, )
})
Name (_DSD, Package () {
ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), // Device Properties UUID
Package () {
Package () { "compatible", "nxp,pca9548" },
Package () { "i2c-mux-idle-disconnect", "" },
}
})
// Unused channels
// Device (CH00) { Name (_ADR, 0) }
// Device (CH01) { Name (_ADR, 1) }
// Device (CH02) { Name (_ADR, 2) }
// Device (CH03) { Name (_ADR, 3) }
// Device (CH04) { Name (_ADR, 4) }
// Device (CH05) { Name (_ADR, 5) }
// Device (CH06) { Name (_ADR, 6) }
// Channel 7 contains GPIO expander.
Device (CH07)
{
Name (_ADR, 7)
}
}
}
}
