Applied to drm-misc-next. Thanks！
在 2018/4/17 5:43, Heiko Stuebner 写道:
Hi John,
Am Montag, 16. April 2018, 18:46:56 CEST schrieb John Keeping:
Hi Sandy,
On Tue, 10 Apr 2018 20:40:06 +0800, Sandy Huang wrote:
Reviewed-by: Sandy huang <h...@rock-chips.com>
Thanks for the review, but I don't see this in drm-misc yet. Are you
planning to pick this up?
I was occupied with merge-window stuff recently, but I guess either
Sandy or myself is going to pick it up shortly.
Heiko
在 2018/3/29 0:03, John Keeping 写道:
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 <j...@metanate.com>
---
drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index 6755a9eea4b2..d4e1400aedf3 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1017,9 +1017,9 @@ static void vop_crtc_atomic_flush(struct drm_crtc *crtc,
continue;
drm_framebuffer_get(old_plane_state->fb);
+ WARN_ON(drm_crtc_vblank_get(crtc) != 0);
drm_flip_work_queue(&vop->fb_unref_work, old_plane_state->fb);
set_bit(VOP_PENDING_FB_UNREF, &vop->pending);
- WARN_ON(drm_crtc_vblank_get(crtc) != 0);
}
}
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