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Remove internal adjustments to framebuffer format from cirrus-qemu driver. The driver did this to support higher resolutions by reducing the per-pixel memory consumption. DRM has a policy of exporting formats as they are implemented in hardware. So avoid internal adjustments if possible. Also remove the call to drm_fb_blit() from cirrus-qemu. The helper is useful if source and destination format are not known beforehand. This is not the case for cirrus-qemu. This change effectively reduces the maximum available resolution to 800x600 at 32 bpp. A maximum scanline pitch of 4095 byte prevents 1024 pixels per scanline at 32 bpp. Higher resolutions are possible at lower bit depths, but are currently not supported by userspace. When cirrus-qemu currently reduced the internal bit depth to support higher resolutions, it trades resolution for bit depth and CPU time. Converting from 32-bit colors has a significant runtime overhead, as outlined at [1]. Avoiding color-format adjustments also avoids this tradeoff. v2: - expand commit message (Gerd) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Link: https://lore.kernel.org/dri-devel/20250325110407.81107-1-tzimmermann@suse.de/ # 1 Link: https://lore.kernel.org/r/20250328091821.195061-4-tzimmermann@suse.de
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 reStructuredText 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.