agp/hp: fail gracefully if we don't find an IOC

Bail out if we don't find an enclosing IOC.  Previously, if we didn't
find one, we tried to set things up using garbage for the SBA/IOC register
address, which causes a crash.

This crash only happens if firmware supplies a defective ACPI namespace, so
it doesn't fix any problems in the field.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/char/agp/hp-agp.c b/drivers/char/agp/hp-agp.c
index dc8a6f7..58752b7 100644 (file)
--- a/drivers/char/agp/hp-agp.c
+++ b/drivers/char/agp/hp-agp.c
@@ -508,6 +508,9 @@ zx1_gart_probe (acpi_handle obj, u32 depth, void *context, void **ret)
                handle = parent;
        } while (ACPI_SUCCESS(status));
 
+       if (ACPI_FAILURE(status))
+               return AE_OK;   /* found no enclosing IOC */
+
        if (hp_zx1_setup(sba_hpa + HP_ZX1_IOC_OFFSET, lba_hpa))
                return AE_OK;