• Mark yao's avatar
    drm/rockchip: fix race with kms hotplug and fbdev · 8415ab56
    Mark yao authored
    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] [<ffffff8008a344f4>] mutex_lock+0x14/0x44
    [    0.756260] [<ffffff8008445708>] drm_fb_helper_hotplug_event+0x30/0x114
    [    0.756271] [<ffffff8008473c84>] rockchip_drm_output_poll_changed+0x18/0x20
    [    0.756280] [<ffffff8008439fcc>] drm_kms_helper_hotplug_event+0x28/0x34
    [    0.756286] [<ffffff800846c444>] cdn_dp_pd_event_work+0x394/0x3c4
    [    0.756295] [<ffffff80080b2b38>] process_one_work+0x218/0x3e0
    [    0.756302] [<ffffff80080b3538>] worker_thread+0x2e8/0x404
    [    0.756308] [<ffffff80080b7e70>] kthread+0xe8/0xf0
    [    0.756316] [<ffffff8008082690>] ret_from_fork+0x10/0x40
    
    [0]: https://01.org/linuxgraphics/gfx-docs/drm/gpu/drm-kms-helpers.htmlSigned-off-by: default avatarMark Yao <mark.yao@rock-chips.com>
    Reviewed-by: default avatarSandy huang <sandy.huang@rock-chips.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/1501575103-20136-1-git-send-email-mark.yao@rock-chips.com
    8415ab56
rockchip_drm_drv.c 11.7 KB