On Tuesday, August 03, 2010, Rafael J. Wysocki wrote:
> On Tuesday, August 03, 2010, Hidetoshi Seto wrote:
> > (2010/08/03 13:52), Kenji Kaneshige wrote:
> > > (2010/08/03 6:59), Rafael J. Wysocki wrote:
> > >> @@ -434,19 +432,6 @@ acpi_status acpi_pci_osc_control_set(acp
> > >> if ((root->osc_control_set& control_req) == control_req)
> > >> goto out;
> > >>
> > >> - /* Need to query controls first before requesting them */
> > >> - if (!root->osc_queried) {
> > >> - status = acpi_pci_query_osc(root, root->osc_support_set, NULL);
> > >> - if (ACPI_FAILURE(status))
> > >> - goto out;
> > >> - }
> > >> - if ((root->osc_control_qry& control_req) != control_req) {
> > >> - printk(KERN_DEBUG
> > >> - "Firmware did not grant requested _OSC control\n");
> > >> - status = AE_SUPPORT;
> > >> - goto out;
> > >> - }
> > >
> > > I think acpi_pci_osc_control_set() still need to query before commit
> > > to ensure all the requested controls are granted to OS.
> > >
> > > So the code needs to be
> > >
> > > status = acpi_pci_query_osc(root, root->osc_support_set, &control_req);
> > > if (ACPI_FAILURE(status))
> > > goto out;
> >
> > Hum, since acpi_status acpi_pci_osc_control_set() is an exported
> > function, we cannot be too careful here.
> >
> > OTOH, I think this second query should be done in caller too,
> > i.e. pcie_port_acpi_setup() in patch [4/8].
> >
> > Now:
> > pcie_port_acpi_setup()
> > {
> > flags = A|B|C|D;
> > acpi_pci_osc_control_query(handle, &flags);
> > /* note: flags might be changed after query */
> > acpi_pci_osc_control_set(handle, flags);
> > }
> >
> > Strictly, it could be like:
> >
> > New:
> > pcie_port_acpi_setup()
> > {
> > flags = A|B|C|D;
> > do {
> > pre_flags = flags;
> > acpi_pci_osc_control_query(handle, &flags);
> > } while (flags && pre_flags != flags);
> > if (flags)
> > acpi_pci_osc_control_set(handle, flags);
> > }
> >
> > IMHO these checks are kind of preventive guard for corner cases,
> > and I suppose it can be implemented by an incremental patch later.
>
> OK
>
> The assumption here is that the BIOS would only mask the bits it's not
> going to grant control of and will do it in a consistent way. So, I guess the
> purpose of the change above would be to protect us from buggy BIOSes.
What about the appended patch (on top of 4/8)?
Rafael
---
drivers/pci/pcie/portdrv_acpi.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
Index: linux-2.6/drivers/pci/pcie/portdrv_acpi.c
===================================================================
--- linux-2.6.orig/drivers/pci/pcie/portdrv_acpi.c
+++ linux-2.6/drivers/pci/pcie/portdrv_acpi.c
@@ -35,7 +35,7 @@ int pcie_port_acpi_setup(struct pci_dev
{
acpi_status status;
acpi_handle handle;
- u32 flags;
+ u32 flags, prev_flags = 0;
if (acpi_pci_disabled)
return 0;
@@ -55,11 +55,14 @@ int pcie_port_acpi_setup(struct pci_dev
flags |= OSC_PCI_EXPRESS_AER_CONTROL;
}
- status = acpi_pci_osc_control_query(handle, &flags);
- if (ACPI_FAILURE(status)) {
- dev_dbg(&port->dev, "ACPI _OSC query failed (code %d)\n",
- status);
- return -ENODEV;
+ while (flags != prev_flags) {
+ prev_flags = flags;
+ status = acpi_pci_osc_control_query(handle, &flags);
+ if (ACPI_FAILURE(status)) {
+ dev_dbg(&port->dev,
+ "ACPI _OSC query failed (code %d)\n", status);
+ return -ENODEV;
+ }
}
if (!(flags & OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL)) {
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