The drm callback ->detect and ->get_modes seems is not power safe, they may be called when device is power off, do register access on detect or get_modes will cause system die. Here is the path call ->detect before analogix_dp power on [<ffffff800843babc>] analogix_dp_detect+0x44/0xdc [<ffffff80083fd840>] drm_helper_probe_single_connector_modes_merge_bits+0xe8/0x41c [<ffffff80083fdb84>] drm_helper_probe_single_connector_modes+0x10/0x18 [<ffffff8008418d24>] drm_mode_getconnector+0xf4/0x304 [<ffffff800840cff0>] drm_ioctl+0x23c/0x390 [<ffffff80081a8adc>] do_vfs_ioctl+0x4b8/0x58c [<ffffff80081a8c10>] SyS_ioctl+0x60/0x88 Cc: Inki Dae <inki.dae at samsung.com> Cc: Sean Paul <seanpaul at chromium.org> Cc: Gustavo Padovan <gustavo.padovan at collabora.co.uk> Cc: "Ville Syrj?l?" <ville.syrjala at linux.intel.com> Signed-off-by: Mark Yao <mark.yao at rock-chips.com> --- Changes in v2: - remove sub device power on/off callback, use pm_runtime_get/put is enough to fix my problem, so will can avoid race to dpms. drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index efac8ab..ff2d328 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1062,11 +1062,15 @@ int analogix_dp_get_modes(struct drm_connector *connector) return 0; } + pm_runtime_get_sync(dp->dev); + if (analogix_dp_handle_edid(dp) == 0) { drm_mode_connector_update_edid_property(&dp->connector, edid); num_modes += drm_add_edid_modes(&dp->connector, edid); } + pm_runtime_put(dp->dev); + if (dp->plat_data->panel) num_modes += drm_panel_get_modes(dp->plat_data->panel); @@ -1106,9 +1110,13 @@ analogix_dp_detect(struct drm_connector *connector, bool force) return connector_status_disconnected; } + pm_runtime_get_sync(dp->dev); + if (!analogix_dp_detect_hpd(dp)) status = connector_status_connected; + pm_runtime_put(dp->dev); + ret = analogix_dp_prepare_panel(dp, false, false); if (ret) DRM_ERROR("Failed to unprepare panel (%d)\n", ret); -- 1.9.1