From: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
[ Upstream commit 7fd5b25499bcec157dd4de9a713425efcf4571cd ]
After commit 92cc68e35863c1c61c449efa2b2daef6e9926048 ("drm/vblank: Use
spin_(un)lock_irq() in drm_crtc_vblank_on()") omapdrm locking is broken:
WARNING: inconsistent lock state
5.8.0-rc2-00483-g92cc68e35863 #13 Tainted: G W
--------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
swapper/0/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
ea98222c (&dev->event_lock#2){?.+.}-{2:2}, at: drm_handle_vblank+0x4c/0x520 [drm]
{HARDIRQ-ON-W} state was registered at:
trace_hardirqs_on+0x9c/0x1ec
_raw_spin_unlock_irq+0x20/0x58
omap_crtc_atomic_enable+0x54/0xa0 [omapdrm]
drm_atomic_helper_commit_modeset_enables+0x218/0x270 [drm_kms_helper]
omap_atomic_commit_tail+0x48/0xc4 [omapdrm]
commit_tail+0x9c/0x190 [drm_kms_helper]
drm_atomic_helper_commit+0x154/0x188 [drm_kms_helper]
drm_client_modeset_commit_atomic+0x228/0x268 [drm]
drm_client_modeset_commit_locked+0x60/0x1d0 [drm]
drm_client_modeset_commit+0x24/0x40 [drm]
drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xa8 [drm_kms_helper]
drm_fb_helper_set_par+0x2c/0x5c [drm_kms_helper]
drm_fb_helper_hotplug_event.part.0+0xa0/0xbc [drm_kms_helper]
drm_kms_helper_hotplug_event+0x24/0x30 [drm_kms_helper]
output_poll_execute+0x1a8/0x1c0 [drm_kms_helper]
process_one_work+0x268/0x800
worker_thread+0x30/0x4e0
kthread+0x164/0x190
ret_from_fork+0x14/0x20
The reason for this is that omapdrm calls drm_crtc_vblank_on() while
holding event_lock taken with spin_lock_irq().
It is not clear why drm_crtc_vblank_on() and drm_crtc_vblank_get() are
called while holding event_lock. I don't see any problem with moving
those calls outside the lock, which is what this patch does.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20200819103021.440288-1-tomi.valkeinen@xxxxxx
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/omapdrm/omap_crtc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index 3c5ddbf30e974..f5e18802e7bc6 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -451,11 +451,12 @@ static void omap_crtc_atomic_enable(struct drm_crtc *crtc,
if (omap_state->manually_updated)
return;
- spin_lock_irq(&crtc->dev->event_lock);
drm_crtc_vblank_on(crtc);
+
ret = drm_crtc_vblank_get(crtc);
WARN_ON(ret != 0);
+ spin_lock_irq(&crtc->dev->event_lock);
omap_crtc_arm_event(crtc);
spin_unlock_irq(&crtc->dev->event_lock);
}
--
2.25.1
