On Wed, Nov 23, 2016 at 12:21:03PM +0100, Tomasz Nowicki wrote:
Hi Bjorn,
On 23.11.2016 00:13, Bjorn Helgaas wrote:
Hi Tomasz,
On Fri, Jun 10, 2016 at 09:55:19PM +0200, Tomasz Nowicki wrote:
Implement pci_acpi_scan_root and other arch-specific call so that ARM64 can start using ACPI to setup and enumerate PCI buses.
Prior to buses enumeration the pci_acpi_scan_root() implementation looks for configuration space start address (obtained through ACPI _CBA method or MCFG interface). If succeed, it uses ECAM library to create new mapping. Then it attaches generic ECAM ops (pci_generic_ecam_ops) which are used for accessing configuration space later on. ...
+static struct acpi_pci_root_ops acpi_pci_root_ops = {
- .release_info = pci_acpi_generic_release_info,
+};
+/* Interface called from ACPI code to setup PCI host controller */ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) {
- /* TODO: Should be revisited when implementing PCI on ACPI */
- return NULL;
- int node = acpi_get_node(root->device->handle);
- struct acpi_pci_generic_root_info *ri;
- struct pci_bus *bus, *child;
- ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
- if (!ri)
return NULL;- ri->cfg = pci_acpi_setup_ecam_mapping(root);
- if (!ri->cfg) {
kfree(ri);return NULL;- }
- acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
This has already been merged, but this isn't right, is it? We're writing a host controller-specific pointer into the single system-wide acpi_pci_root_ops, then passing it on to acpi_pci_root_create().
Today, I think ri->cfg->ops->pci_ops is always &pci_generic_ecam_ops, from this path:
ri->cfg = pci_acpi_setup_ecam_mapping cfg = pci_ecam_create(..., &pci_generic_ecam_ops) cfg = kzalloc(...) cfg->ops = ops # &pci_generic_ecam_ops
But we're about to merge the ECAM quirks series, which will mean it may not be &pci_generic_ecam_ops. Even apart from the ECAM quirks, we should avoid this pattern of putting device-specific info in a single shared structure because it's too difficult to verify that it's correct.
Well spotted. I agree, we need to fix this. How about this: diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c index fb439c7..31c0e1c 100644 --- a/arch/arm64/kernel/pci.c +++ b/arch/arm64/kernel/pci.c @@ -152,33 +152,35 @@ static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
ri = container_of(ci, struct acpi_pci_generic_root_info, common); pci_ecam_free(ri->cfg);
kfree(ci->ops); kfree(ri);}
-static struct acpi_pci_root_ops acpi_pci_root_ops = {
.release_info = pci_acpi_generic_release_info,-};
/* Interface called from ACPI code to setup PCI host controller */ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) { int node = acpi_get_node(root->device->handle); struct acpi_pci_generic_root_info *ri; struct pci_bus *bus, *child;
struct acpi_pci_root_ops *root_ops; ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node); if (!ri) return NULL;root_ops = kzalloc_node(sizeof(*root_ops), GFP_KERNEL, node);if (!root_ops)return NULL;ri->cfg = pci_acpi_setup_ecam_mapping(root); if (!ri->cfg) { kfree(ri);kfree(root_ops); return NULL; }
acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;bus = acpi_pci_root_create(root, &acpi_pci_root_ops, &ri->common,ri->cfg);
root_ops->release_info = pci_acpi_generic_release_info;root_ops->pci_ops = &ri->cfg->ops->pci_ops;bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg); if (!bus) return NULL;Of course, this should be the part of ECAM quirks core patches.
The other option we have is to remove "struct pci_ops *pci_ops;" from acpi_pci_root_ops structure and pass struct pci_ops as an extra argument to acpi_pci_root_create(). What do you think?
I think your patch above is fine and avoids the need to change the x86 and ia64 code. Would you mind packaging this up with a changelog and signed-off-by? I can take care of putting it in the ECAM series.
Thanks, Bjorn