drm/exynos: ipp: Remove Exynos DRM IPP subsystem
Exynos DRM IPP subsystem is in fact non-functional and frankly speaking dead-code. This patch clearly marks that Exynos DRM IPP subsystem is broken and never really functional. It will be replaced by a completely rewritten API. Exynos DRM IPP user-space API can be obsoleted for the following reasons: 1. Exynos DRM IPP user-space API can be optional in Exynos DRM, so userspace should not rely that it is always available and should have a software fallback in case it is not there. 2. The only mode which was initially semi-working was memory-to-memory image processing. The remaining modes (LCD-"writeback" and "output") were never operational due to missing code (both in mainline and even vendor kernels). 3. Exynos DRM IPP mainline user-space API compatibility for memory-to-memory got broken very early by commit 083500ba ("drm: remove DRM_FORMAT_NV12MT", which removed the support for tiled formats, the main feature which made this API somehow useful on Exynos platforms (video codec that time produced only tiled frames, to implement xvideo or any other video overlay, one has to de-tile them for proper display). 4. Broken drivers. Especially once support for IOMMU has been added, it revealed that drivers don't configure DMA operations properly and in many cases operate outside the provided buffers trashing memory around. 5. Need for external patches. Although IPP user-space API has been used in some vendor kernels, but in such cases there were additional patches applied (like reverting mentioned 083500ba patch) what means that those userspace apps which might use it, still won't work with the mainline kernel version. We don't have time machines, so we cannot change it, but Exynos DRM IPP extension should never have been merged to mainline in that form. Exynos IPP subsystem and user-space API will be rewritten, so remove current IPP core code and mark existing drivers as BROKEN. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Daniel Stone <daniels@collabora.com> Acked-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Inki Dae <inki.dae@samsung.com>
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