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?
Thanks,
Tomasz
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