On 16.03.23 12:58, Alexander Stein wrote:
Hi Oliver,
Am Donnerstag, 16. März 2023, 12:17:32 CET schrieb Oliver Neukum:
It seems to me that you must not add a bridge before
pci_create_sysfs_dev_files() has finished. Now you could add a wait_queue
and a flag and wait for it to finish. But that is not very elegant.
Do we need the pci_sysfs_init initcall at all? Or to put it in other words,
what does this initcall solve?
Fundamentally something has to discover the root bridge.
Secondly your system has to boot. The device right behind
the root bridge will already be up and running when the kernel
takes control. IMHO treating such devices differently from
other devices makes sense.
See my different approach eliminating this race at all.
Please elaborate
From which initcall is your driver probed?
The callstack looks like this:
imx6_pcie_probe from platform_probe+0x5c/0xb8
platform_probe from call_driver_probe+0x24/0x118
call_driver_probe from really_probe+0xc4/0x31c
really_probe from __driver_probe_device+0x8c/0x120
__driver_probe_device from driver_probe_device+0x30/0xc0
driver_probe_device from __driver_attach_async_helper+0x50/0xd8
__driver_attach_async_helper from async_run_entry_fn+0x30/0x144
async_run_entry_fn from process_one_work+0x1c4/0x3d0
process_one_work from worker_thread+0x50/0x41c
worker_thread from kthread+0xec/0x104
kthread from ret_from_fork+0x14/0x2c
So technically the device is not probed from within a initcall but a kthread.
It is set to be probed asynchronous in imx6_pcie_driver.
That may be the problem, respectively that system is incomplete
You are registering a PCI bridge. The PCI subsystem should be
done setting up when you run. That is just a simple dependency.
Regards
Oliver
