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| /linux/drivers/gpu/drm/exynos/ |
| H A D | exynos_mixer.c | diff 6a3b45ada960ac475ec2b4103d43e57943b2b8d3 Tue Mar 19 14:05:11 CET 2019 Andrzej Hajda <a.hajda@samsung.com> drm/exynos/mixer: fix MIXER shadow registry synchronisation code
MIXER on Exynos5 SoCs uses different synchronisation method than Exynos4
to update internal state (shadow registers).
Apparently the driver implements it incorrectly. The rule should be
as follows:
- do not request updating registers until previous request was finished,
ie. MXR_CFG_LAYER_UPDATE_COUNT must be 0.
- before setting registers synchronisation on VSYNC should be turned off,
ie. MXR_STATUS_SYNC_ENABLE should be reset,
- after finishing MXR_STATUS_SYNC_ENABLE should be set again.
The patch hopefully implements it correctly.
Below sample kernel log from page fault caused by the bug:
[ 25.670038] exynos-sysmmu 14650000.sysmmu: 14450000.mixer: PAGE FAULT occurred at 0x2247b800
[ 25.677888] ------------[ cut here ]------------
[ 25.682164] kernel BUG at ../drivers/iommu/exynos-iommu.c:450!
[ 25.687971] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
[ 25.693778] Modules linked in:
[ 25.696816] CPU: 5 PID: 1553 Comm: fb-release_test Not tainted 5.0.0-rc7-01157-g5f86b1566bdd #136
[ 25.705646] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 25.711710] PC is at exynos_sysmmu_irq+0x1c0/0x264
[ 25.716470] LR is at lock_is_held_type+0x44/0x64
v2: added missing MXR_CFG_LAYER_UPDATE bit setting in mixer_enable_sync
Reported-by: Marian Mihailescu <mihailescu2m@gmail.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
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