From f244d8b623dae7a7bc695b0336f67729b95a9736 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 31 Dec 2013 13:39:42 +0100 Subject: ACPIPHP / radeon / nouveau: Fix VGA switcheroo problem related to hotplug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reported-and-tested-by: Reported-and-tested-by: Joaquín Aramendía Cc: Alex Deucher Cc: Dave Airlie Cc: Takashi Iwai Signed-off-by: Rafael J. Wysocki Cc: 3.12+ # 3.12+ --- drivers/pci/hotplug/acpiphp_glue.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) (limited to 'drivers/pci') diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 438a4d09958b..e86439283a5d 100644 --- 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) -- cgit v1.2.3