Re: [PATCH 1/1] powerpc/64: Adjust order in pcibios_init()
From: Oliver <oohall@gmail.com>
Date: 2019-02-15 00:57:13
On Thu, Feb 14, 2019 at 4:14 PM Sam Bobroff [off-list ref] wrote:
The pcibios_init() function for 64 bit PowerPC currently calls pci_bus_add_devices() before pcibios_resource_survey(), which seems incorrect because it adds devices and attempts to bind their drivers before allocating their resources (although no problems seem to be apparent). So move the call to pci_bus_add_devices() to after pcibios_resource_survey(). This will also allow the ppc_md.pcibios_bus_add_device() hooks to perform actions that depend on PCI resources, both during rescanning (where this is already the case) and at boot time, which should support improvements and refactoring. Signed-off-by: Sam Bobroff <redacted>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
quoted hunk ↗ jump to hunk
--- Hi everyone, I've tested this on a P9 for both the host and a KVM guest, and the change hasn't caused any differences in PCI resource assignments or the general boot messages. I've also had a go at inspecting most of the code used by pci_bus_add_devices() and pcibios_resource_survey() and it doesn't look like there are going to be any changes in behaviour caused by reordering. It might be worth mentioning that the hotplug path (see pcibios_finish_adding_to_bus()) already does resource allocation before calling pci_bus_add_devices(). However, it would be great if someone could test this change on some older hardware or comment on wether we should make the same change on 32 bit machines. Cheers, Sam. arch/powerpc/kernel/pci_64.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c index 9d8c10d55407..1ce28888dbdb 100644 --- a/arch/powerpc/kernel/pci_64.c +++ b/arch/powerpc/kernel/pci_64.c@@ -58,14 +58,16 @@ static int __init pcibios_init(void) pci_add_flags(PCI_ENABLE_PROC_DOMAINS | PCI_COMPAT_DOMAIN_0); /* Scan all of the recorded PCI controllers. */ - list_for_each_entry_safe(hose, tmp, &hose_list, list_node) { + list_for_each_entry_safe(hose, tmp, &hose_list, list_node) pcibios_scan_phb(hose); - pci_bus_add_devices(hose->bus); - } /* Call common code to handle resource allocation */ pcibios_resource_survey(); + /* Add devices. */ + list_for_each_entry_safe(hose, tmp, &hose_list, list_node) + pci_bus_add_devices(hose->bus); + printk(KERN_DEBUG "PCI: Probing PCI hardware done\n"); return 0; --2.19.0.2.gcad72f5712