From b440bde74f043c8ec31081cb59c9a53ade954701 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Wed, 10 Sep 2014 13:45:01 -0600 Subject: PCI: Add pci_ignore_hotplug() to ignore hotplug events for a device Powering off a hot-pluggable device, e.g., with pci_set_power_state(D3cold), normally generates a hot-remove event that unbinds the driver. Some drivers expect to remain bound to a device even while they power it off and back on again. This can be dangerous, because if the device is removed or replaced while it is powered off, the driver doesn't know that anything changed. But some drivers accept that risk. Add pci_ignore_hotplug() for use by drivers that know their device cannot be removed. Using pci_ignore_hotplug() tells the PCI core that hot-plug events for the device should be ignored. The radeon and nouveau drivers use this to switch between a low-power, integrated GPU and a higher-power, higher-performance discrete GPU. They power off the unused GPU, but they want to remain bound to it. This is a reimplementation of f244d8b623da ("ACPIPHP / radeon / nouveau: Fix VGA switcheroo problem related to hotplug") but extends it to work with both acpiphp and pciehp. This fixes a problem where systems with dual GPUs using the radeon drivers become unusable, freezing every few seconds (see bugzillas below). The resume of the radeon device may also fail, e.g., This fixes problems on dual GPU systems where the radeon driver becomes unusable because of problems while suspending the device, as in bug 79701: [drm] radeon: finishing device. radeon 0000:01:00.0: Userspace still has active objects ! radeon 0000:01:00.0: ffff8800cb4ec288 ffff8800cb4ec000 16384 4294967297 force free ... WARNING: CPU: 0 PID: 67 at /home/apw/COD/linux/drivers/gpu/drm/radeon/radeon_gart.c:234 radeon_gart_unbind+0xd2/0xe0 [radeon]() trying to unbind memory from uninitialized GART ! or while resuming it, as in bug 77261: radeon 0000:01:00.0: ring 0 stalled for more than 10158msec radeon 0000:01:00.0: GPU lockup ... radeon 0000:01:00.0: GPU pci config reset pciehp 0000:00:01.0:pcie04: Card not present on Slot(1-1) radeon 0000:01:00.0: GPU reset succeeded, trying to resume *ERROR* radeon: dpm resume failed radeon 0000:01:00.0: Wait for MC idle timedout ! Link: https://bugzilla.kernel.org/show_bug.cgi?id=77261 Link: https://bugzilla.kernel.org/show_bug.cgi?id=79701 Reported-by: Shawn Starr Reported-by: Jose P. Signed-off-by: Bjorn Helgaas Acked-by: Alex Deucher Acked-by: Rajat Jain Acked-by: Rafael J. Wysocki Acked-by: Dave Airlie CC: stable@vger.kernel.org # v3.15+ --- drivers/gpu/drm/nouveau/nouveau_drm.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/gpu/drm/nouveau/nouveau_drm.c') diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index 250a5e88c751..9c3af96a7153 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -627,6 +627,7 @@ int nouveau_pmops_suspend(struct device *dev) pci_save_state(pdev); pci_disable_device(pdev); + pci_ignore_hotplug(pdev); pci_set_power_state(pdev, PCI_D3hot); return 0; } -- cgit v1.2.3-59-g8ed1b