ACPI/PCI: Negotiate _OSC control bits before requesting them

It is possible that the BIOS will not grant control of all _OSC
features requested via acpi_pci_osc_control_set(), so it is
recommended to negotiate the final set of _OSC features with the
query flag set before calling _OSC to request control of these
features.

To implement it, rework acpi_pci_osc_control_set() so that the caller
can specify the mask of _OSC control bits to negotiate and the mask
of _OSC control bits that are absolutely necessary to it.  Then,
acpi_pci_osc_control_set() will run _OSC queries in a loop until
the mask of _OSC control bits returned by the BIOS is equal to the
mask passed to it.  Also, before running the _OSC request
acpi_pci_osc_control_set() will check if the caller's required
control bits are present in the final mask.

Using this mechanism we will be able to avoid situations in which the
BIOS doesn't grant control of certain _OSC features, because they
depend on some other _OSC features that have not been requested.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 77cd19697b1e9f25a0dc1f64218cf5e37622bdb5..c34713112520a06fc878243cde5aabb43a1861ce 100644 (file)
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -374,21 +374,32 @@ out:
 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
 
 /**
- * acpi_pci_osc_control_set - commit requested control to Firmware
- * @handle: acpi_handle for the target ACPI object
- * @flags: driver's requested control bits
+ * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
+ * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
+ * @mask: Mask of _OSC bits to request control of, place to store control mask.
+ * @req: Mask of _OSC bits the control of is essential to the caller.
  *
- * Attempt to take control from Firmware on requested control bits.
+ * Run _OSC query for @mask and if that is successful, compare the returned
+ * mask of control bits with @req.  If all of the @req bits are set in the
+ * returned mask, run _OSC request for it.
+ *
+ * The variable at the @mask address may be modified regardless of whether or
+ * not the function returns success.  On success it will contain the mask of
+ * _OSC bits the BIOS has granted control of, but its contents are meaningless
+ * on failure.
  **/
-acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags)
+acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 {
+       struct acpi_pci_root *root;
        acpi_status status;
-       u32 control_req, result, capbuf[3];
+       u32 ctrl, capbuf[3];
        acpi_handle tmp;
-       struct acpi_pci_root *root;
 
-       control_req = (flags & OSC_PCI_CONTROL_MASKS);
-       if (!control_req)
+       if (!mask)
+               return AE_BAD_PARAMETER;
+
+       ctrl = *mask & OSC_PCI_CONTROL_MASKS;
+       if ((ctrl & req) != req)
                return AE_TYPE;
 
        root = acpi_pci_find_root(handle);
@@ -400,27 +411,33 @@ acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags)
                return status;
 
        mutex_lock(&osc_lock);
+
+       *mask = ctrl | root->osc_control_set;
        /* No need to evaluate _OSC if the control was already granted. */
-       if ((root->osc_control_set & control_req) == control_req)
+       if ((root->osc_control_set & ctrl) == ctrl)
                goto out;
 
-       /* Need to query controls first before requesting them */
-       flags = control_req;
-       status = acpi_pci_query_osc(root, root->osc_support_set, &flags);
-       if (ACPI_FAILURE(status))
-               goto out;
+       /* Need to check the available controls bits before requesting them. */
+       while (*mask) {
+               status = acpi_pci_query_osc(root, root->osc_support_set, mask);
+               if (ACPI_FAILURE(status))
+                       goto out;
+               if (ctrl == *mask)
+                       break;
+               ctrl = *mask;
+       }
 
-       if (flags != control_req) {
+       if ((ctrl & req) != req) {
                status = AE_SUPPORT;
                goto out;
        }
 
        capbuf[OSC_QUERY_TYPE] = 0;
        capbuf[OSC_SUPPORT_TYPE] = root->osc_support_set;
-       capbuf[OSC_CONTROL_TYPE] = root->osc_control_set | control_req;
-       status = acpi_pci_run_osc(handle, capbuf, &result);
+       capbuf[OSC_CONTROL_TYPE] = ctrl;
+       status = acpi_pci_run_osc(handle, capbuf, mask);
        if (ACPI_SUCCESS(status))
-               root->osc_control_set = result;
+               root->osc_control_set = *mask;
 out:
        mutex_unlock(&osc_lock);
        return status;
@@ -551,8 +568,8 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
        if (flags != base_flags)
                acpi_pci_osc_support(root, flags);
 
-       status = acpi_pci_osc_control_set(root->device->handle,
-                                         OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
+       flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL;
+       status = acpi_pci_osc_control_set(root->device->handle, &flags, flags);
 
        if (ACPI_FAILURE(status)) {
                printk(KERN_INFO "Unable to assume PCIe control: Disabling ASPM\n");

diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
index 45fcc1e96df9ac08718696e7ea8a8f487f33072f..3d93d529a7bd0ef2e05237e87c359bc16879a723 100644 (file)
--- a/drivers/pci/hotplug/acpi_pcihp.c
+++ b/drivers/pci/hotplug/acpi_pcihp.c
@@ -360,7 +360,7 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev, u32 flags)
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
                dbg("Trying to get hotplug control for %s\n",
                                (char *)string.pointer);
-               status = acpi_pci_osc_control_set(handle, flags);
+               status = acpi_pci_osc_control_set(handle, &flags, flags);
                if (ACPI_SUCCESS(status))
                        goto got_one;
                if (status == AE_SUPPORT)

diff --git a/drivers/pci/pcie/aer/aerdrv_acpi.c b/drivers/pci/pcie/aer/aerdrv_acpi.c
index f278d7b0d95d32b636260cddbe763aa109fbfacf..3a276a0cea9325385895b1d3ff5623882605d397 100644 (file)
--- a/drivers/pci/pcie/aer/aerdrv_acpi.c
+++ b/drivers/pci/pcie/aer/aerdrv_acpi.c
@@ -39,9 +39,9 @@ int aer_osc_setup(struct pcie_device *pciedev)
 
        handle = acpi_find_root_bridge_handle(pdev);
        if (handle) {
-               status = acpi_pci_osc_control_set(handle,
-                                       OSC_PCI_EXPRESS_AER_CONTROL |
-                                       OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
+               u32 flags = OSC_PCI_EXPRESS_AER_CONTROL |
+                               OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL;
+               status = acpi_pci_osc_control_set(handle, &flags, flags);
        }
 
        if (ACPI_FAILURE(status)) {

diff --git a/drivers/pci/pcie/pme/pcie_pme_acpi.c b/drivers/pci/pcie/pme/pcie_pme_acpi.c
index 83ab2287ae3f86bc501ddf64b2a7d1f09991e1f5..be20222b12d3ed630699c9dcc3a50f590f2b7cb8 100644 (file)
--- a/drivers/pci/pcie/pme/pcie_pme_acpi.c
+++ b/drivers/pci/pcie/pme/pcie_pme_acpi.c
@@ -28,6 +28,7 @@ int pcie_pme_acpi_setup(struct pcie_device *srv)
        acpi_status status = AE_NOT_FOUND;
        struct pci_dev *port = srv->port;
        acpi_handle handle;
+       u32 flags;
        int error = 0;
 
        if (acpi_pci_disabled)
@@ -39,9 +40,10 @@ int pcie_pme_acpi_setup(struct pcie_device *srv)
        if (!handle)
                return -EINVAL;
 
-       status = acpi_pci_osc_control_set(handle,
-                       OSC_PCI_EXPRESS_PME_CONTROL |
-                       OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
+       flags = OSC_PCI_EXPRESS_PME_CONTROL |
+               OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL;
+
+       status = acpi_pci_osc_control_set(handle, &flags, flags);
        if (ACPI_FAILURE(status)) {
                dev_info(&port->dev,
                        "Failed to receive control of PCIe PME service: %s\n",

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index ccf94dc5acdf0ba8cc4f836968f103f542ff43b6..c227757feb06b4c22eb15ca3faf82c1dfa9f107e 100644 (file)
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -304,8 +304,8 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
                                OSC_PCI_EXPRESS_PME_CONTROL |           \
                                OSC_PCI_EXPRESS_AER_CONTROL |           \
                                OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL)
-
-extern acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags);
+extern acpi_status acpi_pci_osc_control_set(acpi_handle handle,
+                                            u32 *mask, u32 req);
 extern void acpi_early_init(void);
 
 #else  /* !CONFIG_ACPI */