Thomas Zimmermann
cf1ca9aeb9
drm/fb-helper: Map DRM client buffer only when required
This patch changes DRM clients to not map the buffer by default. The buffer, like any buffer object, should be mapped and unmapped when needed. An unmapped buffer object can be evicted to system memory and does not consume video ram until displayed. This allows to use generic fbdev emulation with drivers for low-memory devices, such as ast and mgag200. This change affects the generic framebuffer console. HW-based consoles map their console buffer once and keep it mapped. Userspace can mmap this buffer into its address space. The shadow-buffered framebuffer console only needs the buffer object to be mapped during updates. While not being updated from the shadow buffer, the buffer object can remain unmapped. Userspace will always mmap the shadow buffer. v2: * change DRM client to not map buffer by default * manually map client buffer for fbdev with HW framebuffer Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Noralf Trønnes <noralf@tronnes.org> Link: https://patchwork.freedesktop.org/patch/315830/
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.
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