From 8415ab565da966b2bf85ed9322784cd15770a66e Mon Sep 17 00:00:00 2001 From: Mark yao Date: Tue, 1 Aug 2017 16:11:43 +0800 Subject: [PATCH] drm/rockchip: fix race with kms hotplug and fbdev According to the kerneldoc[0], should do fbdev setup before calling drm_kms_helper_poll_init(), otherwise, Kms hotplug event may race into fbdev helper initial, and fb_helper->dev may be NULL pointer, that would cause the bug: [ 0.735411] [00000200] *pgd=00000000f6ffe003, *pud=00000000f6ffe003, *pmd=0000000000000000 [ 0.736156] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 0.736648] Modules linked in: [ 0.736930] CPU: 2 PID: 20 Comm: kworker/2:0 Not tainted 4.4.41 #20 [ 0.737480] Hardware name: Rockchip RK3399 Board rev2 (BOX) (DT) [ 0.738020] Workqueue: events cdn_dp_pd_event_work [ 0.738447] task: ffffffc0f21f3100 ti: ffffffc0f2218000 task.ti: ffffffc0f2218000 [ 0.739109] PC is at mutex_lock+0x14/0x44 [ 0.739469] LR is at drm_fb_helper_hotplug_event+0x30/0x114 [ 0.756253] [] mutex_lock+0x14/0x44 [ 0.756260] [] drm_fb_helper_hotplug_event+0x30/0x114 [ 0.756271] [] rockchip_drm_output_poll_changed+0x18/0x20 [ 0.756280] [] drm_kms_helper_hotplug_event+0x28/0x34 [ 0.756286] [] cdn_dp_pd_event_work+0x394/0x3c4 [ 0.756295] [] process_one_work+0x218/0x3e0 [ 0.756302] [] worker_thread+0x2e8/0x404 [ 0.756308] [] kthread+0xe8/0xf0 [ 0.756316] [] ret_from_fork+0x10/0x40 [0]: https://01.org/linuxgraphics/gfx-docs/drm/gpu/drm-kms-helpers.html Signed-off-by: Mark Yao Reviewed-by: Sandy huang Link: https://patchwork.freedesktop.org/patch/msgid/1501575103-20136-1-git-send-email-mark.yao@rock-chips.com --- drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c index 848edcf2221a..c41f48ae7913 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c @@ -161,22 +161,21 @@ static int rockchip_drm_bind(struct device *dev) */ drm_dev->irq_enabled = true; - /* init kms poll for handling hpd */ - drm_kms_helper_poll_init(drm_dev); - ret = rockchip_drm_fbdev_init(drm_dev); if (ret) - goto err_kms_helper_poll_fini; + goto err_unbind_all; + + /* init kms poll for handling hpd */ + drm_kms_helper_poll_init(drm_dev); ret = drm_dev_register(drm_dev, 0); if (ret) - goto err_fbdev_fini; + goto err_kms_helper_poll_fini; return 0; -err_fbdev_fini: - rockchip_drm_fbdev_fini(drm_dev); err_kms_helper_poll_fini: drm_kms_helper_poll_fini(drm_dev); + rockchip_drm_fbdev_fini(drm_dev); err_unbind_all: component_unbind_all(dev, drm_dev); err_mode_config_cleanup: -- 2.20.1