On 12/01/2016 02:20 PM, Mark Salter wrote:
> On Thu, 2016-12-01 at 12:33 -0600, Bjorn Helgaas wrote:
>>> + csr = &xgene_v1_csr_res[root->segment];
>> This makes me nervous because root->segment comes from the ACPI _SEG,
>> and if firmware gives us junk in _SEG, we will reference something in
>> the weeds.
>
> The SoC provide some number of RC bridges, each with a different base
> for some mmio registers. Even if segment is legitimate in MCFG, there
> is still a problem if a platform doesn't use the segment ordering
> implied by the code. But the PNP0A03 _CRS does have this base address
> as the first memory resource, so we could get it from there and not
> have hard-coded addresses and implied ording in the quirk code.
>
> I have tested a modified version of these quirks using this to
> get the CSR base and it works on the 3 different platforms I have
> access to.
>
> static int xgene_pcie_get_csr(struct device *dev, struct resource *r)
> {
> struct acpi_device *adev = to_acpi_device(dev);
> unsigned long flags;
> struct list_head list;
> struct resource_entry *entry;
> int ret;
>
> INIT_LIST_HEAD(&list);
> flags = IORESOURCE_MEM;
> ret = acpi_dev_get_resources(adev, &list,
> acpi_dev_filter_resource_type_cb,
> (void *)flags);
> if (ret < 0) {
> dev_err(dev, "failed to parse _CRS, error: %d\n", ret);
> return ret;
> } else if (ret == 0) {
> dev_err(dev, "no memory resources present in _CRS\n");
> return -EINVAL;
> }
>
> entry = list_first_entry(&list, struct resource_entry, node);
> *r = *entry->res;
> acpi_dev_free_resource_list(&list);
> return 0;
> }
This seems a lot safer. At some point trusting firmware to provide the
correct _CRS for the RC in use is better than hard coding for every
possible implementation configuration of an X-Gene SoC.
Jon.
--
Computer Architect | Sent from my Fedora powered laptop
