PCI: ignore bit0 of _OSC return code

Currently acpi_run_osc() checks all the bits in _OSC result code (the
first DWORD in the capabilities buffer) to see error condition. But the
bit 0, which doesn't indicate any error, must be ignored.

The bit 0 is used as the query flag at _OSC invocation time. Some
platforms clear it during _OSC evaluation, but the others don't. On
latter platforms, current acpi_run_osc() mis-detects error when _OSC is
evaluated with query flag set because it doesn't ignore the bit 0.
Because of this, the __acpi_query_osc() always fails on such platforms.

And this is the cause of the problem that pci_osc_control_set() doesn't
work since the commit 4e39432f4df544d3dfe4fc90a22d87de64d15815 which
changed pci_osc_control_set() to use __acpi_query_osc().

Tested-by:"Tomasz Czernecki <czernecki@gmail.com>
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index b3a63edb6901..ae5ec76dca77 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -63,7 +63,7 @@ static acpi_status acpi_run_osc(acpi_handle handle,
         union acpi_object in_params[4];
         struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
         union acpi_object *out_obj;
-        u32 osc_dw0, flags = osc_args->capbuf[OSC_QUERY_TYPE];
+        u32 errors, flags = osc_args->capbuf[OSC_QUERY_TYPE];
 
         /* Setting up input parameters */
         input.count = 4;
@@ -92,15 +92,16 @@ static acpi_status acpi_run_osc(acpi_handle handle,
                 status = AE_TYPE;
                 goto out_kfree;
         }
-        osc_dw0 = *((u32 *)out_obj->buffer.pointer);
-        if (osc_dw0) {
-                if (osc_dw0 & OSC_REQUEST_ERROR)
+        /* Need to ignore the bit0 in result code */
+        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
+        if (errors) {
+                if (errors & OSC_REQUEST_ERROR)
                         printk(KERN_DEBUG "_OSC request fails\n"); 
-                if (osc_dw0 & OSC_INVALID_UUID_ERROR)
+                if (errors & OSC_INVALID_UUID_ERROR)
                         printk(KERN_DEBUG "_OSC invalid UUID\n"); 
-                if (osc_dw0 & OSC_INVALID_REVISION_ERROR)
+                if (errors & OSC_INVALID_REVISION_ERROR)
                         printk(KERN_DEBUG "_OSC invalid revision\n"); 
-                if (osc_dw0 & OSC_CAPABILITIES_MASK_ERROR) {
+                if (errors & OSC_CAPABILITIES_MASK_ERROR) {
                         if (flags & OSC_QUERY_ENABLE)
                                 goto out_success;
                         printk(KERN_DEBUG "_OSC FW not grant req. control\n");