From 0a6e21056eaa859353945c4b164f3ef574d84271 Mon Sep 17 00:00:00 2001 From: Larry Finger Date: Mon, 31 Oct 2016 12:19:39 -0400 Subject: [PATCH] drm/radeon: Fix kernel panic on shutdown Since commit a481daa88fd4 ("drm/radeon: always apply pci shutdown callbacks"), a Dell Latitude D600 laptop has crashed on shutdown. The PCI Identification of the graphics adapter is "VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV250/M9 GL [Mobility FireGL 9000/Radeon 9000] [1002:4c66] (rev 01)". Prior to commit b0c80bd5d2e3 ("drm/radeon: fix up dp aux tear down (v2)"), I have no idea where the panic happened as the screen was blanked before the crash. Since that more recent change, the panic has been in routine radeon_connector_unregister(), and has been shown to be due to a NULL value in the ddc_bus member of struct drm_connector. Bug: https://bugzilla.kernel.org/show_bug.cgi?id=178421 Fixes: a481daa88fd4 ("drm/radeon: always apply pci shutdown callbacks") Signed-off-by: Larry Finger Cc: Alex Deucher Signed-off-by: Alex Deucher --- drivers/gpu/drm/radeon/radeon_connectors.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c index e18839d52e3e..27affbde058c 100644 --- a/drivers/gpu/drm/radeon/radeon_connectors.c +++ b/drivers/gpu/drm/radeon/radeon_connectors.c @@ -931,7 +931,7 @@ static void radeon_connector_unregister(struct drm_connector *connector) { struct radeon_connector *radeon_connector = to_radeon_connector(connector); - if (radeon_connector->ddc_bus->has_aux) { + if (radeon_connector->ddc_bus && radeon_connector->ddc_bus->has_aux) { drm_dp_aux_unregister(&radeon_connector->ddc_bus->aux); radeon_connector->ddc_bus->has_aux = false; } -- 2.20.1