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c0b57581b7
In the previous SoC, the M4U HW is in the EMI power domain which is always on. the latest M4U is in the display power domain which may be turned on/off, thus we have to add pm_runtime interface for it. When the engine work, the engine always enable the power and clocks for smi-larb/smi-common, then the M4U's power will always be powered on automatically via the device link with smi-common. Note: we don't enable the M4U power in iommu_map/unmap for tlb flush. If its power already is on, of course it is ok. if the power is off, the main tlb will be reset while M4U power on, thus the tlb flush while m4u power off is unnecessary, just skip it. Therefore, we increase the ref_count for pm when pm status is ACTIVE, otherwise, skip it. Meanwhile, the tlb_flush_range is called so often, thus, update pm ref_count while the SoC has power-domain to avoid touch the dev->power.lock. and the tlb_flush_all only is called when boot, so no need check if the SoC has power-domain to keep code clean. There will be one case that pm runctime status is not expected when tlb flush. After boot, the display may call dma_alloc_attrs before it call pm_runtime_get(disp-dev), then the m4u's pm status is not active inside the dma_alloc_attrs. Since it only happens after boot, the tlb is clean at that time, I also think this is ok. Signed-off-by: Yong Wu <yong.wu@mediatek.com> Reviewed-by: Tomasz Figa <tfiga@chromium.org> Link: https://lore.kernel.org/r/20210111111914.22211-21-yong.wu@mediatek.com Signed-off-by: Will Deacon <will@kernel.org> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.