On 5/23/2018 3:53 PM, Bjorn Helgaas wrote: > On Wed, May 23, 2018 at 03:10:39PM -0400, Sinan Kaya wrote: >>> If that doesn't work or you'd rather brute-force it, you could try >>> doing something like "pci=earlydump". This is currently only >>> implemented for x86, so it would be some work to implement something >>> similar for arm64. It would be a nice upstream addition if you *did* >>> implement it. >>> >>> In the earlydump output I would be looking for clues about the power >>> state of 03:00.0 to try to figure out if the bootloader left it powered >>> off or if Linux is doing something to turn it off. >>> >> >> Is it really possible to implement a generic version of this? >> >> PCI on ARM64 is not really unified. There are several host bridge drivers >> for different types of access. >> >> If we limit the functionality to ACPI, the answer is still maybe if we >> can pass the base address of the MMCONFIG region. >> >> All products use a different MMCONFIG region. > > On x86, early dump is implemented off to the side, outside the PCI > core, and it takes advantage of arch-specific knowledge about ways to > perform config accesses. > > But I could imagine something in the pci_scan_device() area, where we > have the normal config accessors but we haven't yet touched the > device. I think we could get 99% of the early dump utility in a > completely generic way. > > There might be a few hand-crafted arch-specific quirks that touch PCI > devices even before that point, but those should be pretty rare. I see, you just want to dump the config space of each device as code is walking the bus while scanning. This should be doable. I'll see what I can do. > > Bjorn > -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
