John Keeping 2d078c2d04 drm/rockchip: fix VOP vblank race ... We have seen a case of a bad reference count for vblanks with the Rockchip VOP: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 383 at drivers/gpu/drm/drm_irq.c:1198 drm_vblank_put+0x40/0xcc Modules linked in: brcmfmac brcmutil CPU: 1 PID: 383 Comm: kworker/u8:2 Not tainted 4.9.75-rt60 #1 Hardware name: Rockchip (Device Tree) Workqueue: events_unbound flip_worker Backtrace: [<c010b7b0>] (dump_backtrace) from [<c010ba4c>] (show_stack+0x18/0x1c) r7:c0b1b13c r6:600b0013 r5:00000000 r4:c0b1b13c [<c010ba34>] (show_stack) from [<c032d248>] (dump_stack+0x78/0x94) [<c032d1d0>] (dump_stack) from [<c011e6e8>] (__warn+0xe4/0x104) r7:00000009 r6:c03cf26c r5:00000000 r4:00000000 [<c011e604>] (__warn) from [<c011e7c0>] (warn_slowpath_null+0x28/0x30) r9:eeb443a0 r8:eeb443c8 r7:ee8a5ec0 r6:ee8a5ec0 r5:edb47f00 r4:ee096200 [<c011e798>] (warn_slowpath_null) from [<c03cf26c>] (drm_vblank_put+0x40/0xcc) [<c03cf22c>] (drm_vblank_put) from [<c03cf310>] (drm_crtc_vblank_put+0x18/0x1c) r5:edb47f00 r4:ee3c8a80 [<c03cf2f8>] (drm_crtc_vblank_put) from [<c03ef9b4>] (vop_fb_unref_worker+0x18/0x24) [<c03ef99c>] (vop_fb_unref_worker) from [<c03df194>] (flip_worker+0x98/0xb4) r5:edb47f00 r4:eeb443a8 [<c03df0fc>] (flip_worker) from [<c0134808>] (process_one_work+0x1a8/0x2fc) r9:00000000 r8:ee807d00 r7:00000000 r6:ee809c00 r5:eeb443a8 r4:edfe5f80 [<c0134660>] (process_one_work) from [<c01358ec>] (worker_thread+0x2ac/0x458) r10:00000088 r9:edfe5f98 r8:ee809c2c r7:c0b04100 r6:ee809c00 r5:ee809c00 r4:edfe5f80 [<c0135640>] (worker_thread) from [<c013a0bc>] (kthread+0xfc/0x10c) r10:00000000 r9:00000000 r8:c0135640 r7:edfe5f80 r6:00000000 r5:edf0e240 r4:ee8a4000 r3:ed194e00 [<c0139fc0>] (kthread) from [<c0107cb8>] (ret_from_fork+0x14/0x3c) r8:00000000 r7:00000000 r6:00000000 r5:c0139fc0 r4:edf0e240 ---[ end trace 0000000000000002 ]--- It seems that this is caused by unfortunate timing between vop_crtc_atomic_flush() and vop_handle_vblank() given the following ordering: atomic_flush handle_vblank ------------ ------------- drm_flip_work_queue set_bit if (test_and_clear_bit(...)) drm_flip_work_commit drm_vblank_get This results in vop_fb_unref_worker (called as flip work) decrementing the vblank refcount before it has been incremented. Signed-off-by: John Keeping <john@metanate.com> Reviewed-by: Sandy huang <hjc@rock-chips.com> Signed-off-by: Sandy Huang <hjc@rock-chips.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180328160351.23763-1-john@metanate.com		2018-04-17 09:18:16 +08:00
..
analogix_dp-rockchip.c	drm/bridge: analogix_dp: Don't change psr while bridge is disabled	2018-03-14 11:29:31 +01:00
cdn-dp-core.c	drm/rockchip: cdn-dp: remove the DP phy switch	2018-03-16 11:51:11 +01:00
cdn-dp-core.h
cdn-dp-reg.c
cdn-dp-reg.h
dw_hdmi-rockchip.c	drm/rockchip: dw_hdmi: Move HDMI vpll clock enable to bind()	2018-03-08 17:32:53 +01:00
dw-mipi-dsi.c	drm/rockchip: dw-mipi-dsi: Fix connector and encoder cleanup.	2018-03-08 17:32:52 +01:00
inno_hdmi.c	drm/rockchip: inno_hdmi: reorder clk_disable_unprepare call in unbind	2018-03-08 17:32:52 +01:00
inno_hdmi.h
Kconfig
Makefile
rockchip_drm_drv.c	drm/rockchip: Don't use atomic constructs for psr	2018-03-08 23:28:53 +01:00
rockchip_drm_drv.h	drm/rockchip: Don't use atomic constructs for psr	2018-03-08 23:28:53 +01:00
rockchip_drm_fb.c
rockchip_drm_fb.h
rockchip_drm_fbdev.c
rockchip_drm_fbdev.h
rockchip_drm_gem.c	drm/rockchip: fixup comment for gem_free_object_unlocked	2018-03-28 17:07:36 +02:00
rockchip_drm_gem.h	drm/rockchip: support prime import sg table	2018-02-18 11:16:40 +01:00
rockchip_drm_psr.c	drm/rockchip: Don't use atomic constructs for psr	2018-03-08 23:28:53 +01:00
rockchip_drm_psr.h	drm/rockchip: analogix_dp: set psr activate/deactivate when enable/disable bridge	2018-03-08 23:07:01 +01:00
rockchip_drm_vop.c	drm/rockchip: fix VOP vblank race	2018-04-17 09:18:16 +08:00
rockchip_drm_vop.h
rockchip_lvds.c
rockchip_lvds.h
rockchip_vop_reg.c
rockchip_vop_reg.h