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[ Upstream commit 6a3b45ada9 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>