4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Lyude Paul <[email protected]> [ Upstream commit cae9ff036eea577856d5b12860b4c79c5e71db4a ] As it turns out, on cards that actually have CRTCs on them we're already calling drm_kms_helper_poll_enable(drm_dev) from nouveau_display_resume() before we call it in nouveau_pmops_runtime_resume(). This leads us to accidentally trying to enable polling twice, which results in a potential deadlock between the RPM locks and drm_dev->mode_config.mutex if we end up trying to enable polling the second time while output_poll_execute is running and holding the mode_config lock. As such, make sure we only enable polling in nouveau_pmops_runtime_resume() if we need to. This fixes hangs observed on the ThinkPad W541 Signed-off-by: Lyude <[email protected]> Cc: Hans de Goede <[email protected]> Cc: Kilian Singer <[email protected]> Cc: Lukas Wunner <[email protected]> Cc: David Airlie <[email protected]> Signed-off-by: Dave Airlie <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/gpu/drm/nouveau/nouveau_display.c | 3 ++- drivers/gpu/drm/nouveau/nouveau_drm.c | 5 ++++- 2 files changed, 6 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -370,7 +370,8 @@ nouveau_display_init(struct drm_device * return ret; /* enable polling for external displays */ - drm_kms_helper_poll_enable(dev); + if (!dev->mode_config.poll_enabled) + drm_kms_helper_poll_enable(dev); /* enable hotplug interrupts */ list_for_each_entry(connector, &dev->mode_config.connector_list, head) { --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -743,7 +743,10 @@ nouveau_pmops_runtime_resume(struct devi pci_set_master(pdev); ret = nouveau_do_resume(drm_dev, true); - drm_kms_helper_poll_enable(drm_dev); + + if (!drm_dev->mode_config.poll_enabled) + drm_kms_helper_poll_enable(drm_dev); + /* do magic */ nvif_mask(&device->object, 0x088488, (1 << 25), (1 << 25)); vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_ON);
