ACPIPHP / radeon / nouveau: Fix VGA switcheroo problem related to hotplug

The changes in the ACPI-based PCI hotplug (ACPIPHP) subsystem made
during the 3.12 development cycle uncovered a problem with VGA
switcheroo that on some systems, when the device-specific method
(ATPX in the radeon case, _DSM in the nouveau case) is used to turn
off the discrete graphics, the BIOS generates ACPI hotplug events for
that device and those events cause ACPIPHP to attempt to remove the
device from the system (they are events for a device that was present
previously and is not present any more, so that's what should be done
according to the spec).  Then, the system stops functioning correctly.

Since the hotplug events in question were simply silently ignored
previously, the least intrusive way to address that problem is to
make ACPIPHP ignore them again.  For this purpose, introduce a new
ACPI device flag, no_hotplug, and modify ACPIPHP to ignore hotplug
events for PCI devices whose ACPI companions have that flag set.
Next, make the radeon and nouveau switcheroo detection code set the
no_hotplug flag for the discrete graphics' ACPI companion.

Fixes: bbd34fcdd1b2 (ACPI / hotplug / PCI: Register all devices under the given bridge)
References: https://bugzilla.kernel.org/show_bug.cgi?id=61891
References: https://bugzilla.kernel.org/show_bug.cgi?id=64891
Reported-and-tested-by: Mike Lothian <mike@fireburn.co.uk>
Reported-and-tested-by: <madcatx@atlas.cz>
Reported-and-tested-by: Joaquín Aramendía <samsagax@gmail.com>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 3.12+ <stable@vger.kernel.org> # 3.12+

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index bba9b72e25f8235e6d12593bdd16bb378c7af25a..0710004055c809f3059cde2337373503666fd96f 100644 (file)
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -156,6 +156,16 @@ int acpi_bus_get_private_data(acpi_handle handle, void **data)
 }
 EXPORT_SYMBOL(acpi_bus_get_private_data);
 
+void acpi_bus_no_hotplug(acpi_handle handle)
+{
+       struct acpi_device *adev = NULL;
+
+       acpi_bus_get_device(handle, &adev);
+       if (adev)
+               adev->flags.no_hotplug = true;
+}
+EXPORT_SYMBOL_GPL(acpi_bus_no_hotplug);
+
 static void acpi_print_osc_error(acpi_handle handle,
        struct acpi_osc_context *context, char *error)
 {

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index 95c740454049ad1b4a4cf23c2bc63d7038c7a362..ba0183fb84f3b871a4815552021174e870f780e8 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -51,6 +51,7 @@ static struct nouveau_dsm_priv {
        bool dsm_detected;
        bool optimus_detected;
        acpi_handle dhandle;
+       acpi_handle other_handle;
        acpi_handle rom_handle;
 } nouveau_dsm_priv;
 
@@ -260,9 +261,10 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev)
        if (!dhandle)
                return false;
 
-       if (!acpi_has_method(dhandle, "_DSM"))
+       if (!acpi_has_method(dhandle, "_DSM")) {
+               nouveau_dsm_priv.other_handle = dhandle;
                return false;
-
+       }
        if (nouveau_test_dsm(dhandle, nouveau_dsm, NOUVEAU_DSM_POWER))
                retval |= NOUVEAU_DSM_HAS_MUX;
 
@@ -338,6 +340,16 @@ static bool nouveau_dsm_detect(void)
                printk(KERN_INFO "VGA switcheroo: detected DSM switching method %s handle\n",
                        acpi_method_name);
                nouveau_dsm_priv.dsm_detected = true;
+               /*
+                * On some systems hotplug events are generated for the device
+                * being switched off when _DSM is executed.  They cause ACPI
+                * hotplug to trigger and attempt to remove the device from
+                * the system, which causes it to break down.  Prevent that from
+                * happening by setting the no_hotplug flag for the involved
+                * ACPI device objects.
+                */
+               acpi_bus_no_hotplug(nouveau_dsm_priv.dhandle);
+               acpi_bus_no_hotplug(nouveau_dsm_priv.other_handle);
                ret = true;
        }
 

diff --git a/drivers/gpu/drm/radeon/radeon_atpx_handler.c b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
index 9d302eaeea1587b6fdb5439119b6f45c0de961db..485848f889f55c9f4b86bf61bd8c019e2ad96a27 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_atpx_handler.c
+++ b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
@@ -33,6 +33,7 @@ static struct radeon_atpx_priv {
        bool atpx_detected;
        /* handle for device - and atpx */
        acpi_handle dhandle;
+       acpi_handle other_handle;
        struct radeon_atpx atpx;
 } radeon_atpx_priv;
 
@@ -451,9 +452,10 @@ static bool radeon_atpx_pci_probe_handle(struct pci_dev *pdev)
                return false;
 
        status = acpi_get_handle(dhandle, "ATPX", &atpx_handle);
-       if (ACPI_FAILURE(status))
+       if (ACPI_FAILURE(status)) {
+               radeon_atpx_priv.other_handle = dhandle;
                return false;
-
+       }
        radeon_atpx_priv.dhandle = dhandle;
        radeon_atpx_priv.atpx.handle = atpx_handle;
        return true;
@@ -530,6 +532,16 @@ static bool radeon_atpx_detect(void)
                printk(KERN_INFO "VGA switcheroo: detected switching method %s handle\n",
                       acpi_method_name);
                radeon_atpx_priv.atpx_detected = true;
+               /*
+                * On some systems hotplug events are generated for the device
+                * being switched off when ATPX is executed.  They cause ACPI
+                * hotplug to trigger and attempt to remove the device from
+                * the system, which causes it to break down.  Prevent that from
+                * happening by setting the no_hotplug flag for the involved
+                * ACPI device objects.
+                */
+               acpi_bus_no_hotplug(radeon_atpx_priv.dhandle);
+               acpi_bus_no_hotplug(radeon_atpx_priv.other_handle);
                return true;
        }
        return false;

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 438a4d09958baa26d1d6c670fb6d75bd588e0614..e86439283a5d1911933eed185e22a50146093968 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -645,6 +645,24 @@ static void disable_slot(struct acpiphp_slot *slot)
        slot->flags &= (~SLOT_ENABLED);
 }
 
+static bool acpiphp_no_hotplug(acpi_handle handle)
+{
+       struct acpi_device *adev = NULL;
+
+       acpi_bus_get_device(handle, &adev);
+       return adev && adev->flags.no_hotplug;
+}
+
+static bool slot_no_hotplug(struct acpiphp_slot *slot)
+{
+       struct acpiphp_func *func;
+
+       list_for_each_entry(func, &slot->funcs, sibling)
+               if (acpiphp_no_hotplug(func_to_handle(func)))
+                       return true;
+
+       return false;
+}
 
 /**
  * get_slot_status - get ACPI slot status
@@ -703,7 +721,8 @@ static void trim_stale_devices(struct pci_dev *dev)
                unsigned long long sta;
 
                status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
-               alive = ACPI_SUCCESS(status) && sta == ACPI_STA_ALL;
+               alive = (ACPI_SUCCESS(status) && sta == ACPI_STA_ALL)
+                       || acpiphp_no_hotplug(handle);
        }
        if (!alive) {
                u32 v;
@@ -743,8 +762,9 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
                struct pci_dev *dev, *tmp;
 
                mutex_lock(&slot->crit_sect);
-               /* wake up all functions */
-               if (get_slot_status(slot) == ACPI_STA_ALL) {
+               if (slot_no_hotplug(slot)) {
+                       ; /* do nothing */
+               } else if (get_slot_status(slot) == ACPI_STA_ALL) {
                        /* remove stale devices if any */
                        list_for_each_entry_safe(dev, tmp, &bus->devices,
                                                 bus_list)

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 7b2de026a4f3db11c730d9d3abfa8b903ba5713f..ca49ebd231ca8822160d7ccb349ef3d60386de73 100644 (file)
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -168,7 +168,8 @@ struct acpi_device_flags {
        u32 ejectable:1;
        u32 power_manageable:1;
        u32 match_driver:1;
-       u32 reserved:27;
+       u32 no_hotplug:1;
+       u32 reserved:26;
 };
 
 /* File System */
@@ -343,6 +344,7 @@ extern struct kobject *acpi_kobj;
 extern int acpi_bus_generate_netlink_event(const char*, const char*, u8, int);
 void acpi_bus_private_data_handler(acpi_handle, void *);
 int acpi_bus_get_private_data(acpi_handle, void **);
+void acpi_bus_no_hotplug(acpi_handle handle);
 extern int acpi_notifier_call_chain(struct acpi_device *, u32, u32);
 extern int register_acpi_notifier(struct notifier_block *);
 extern int unregister_acpi_notifier(struct notifier_block *);