fbdev: Warn on incorrect framebuffer access

Test in framebuffer read, write and drawing helpers if FBINFO_VIRTFB
has been set correctly. Framebuffers in I/O memory should only be
accessed with the architecture's respective helpers. Framebuffers
in system memory should be accessed with the regular load and
store operations. Presumably not all drivers get this right, so we
now warn about it.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231127131655.4020-32-tzimmermann@suse.de

fbdev: Fix cfb_imageblit() for arbitrary image widths

Commit 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
broke cfb_imageblit() for image widths that are not aligned to 8-bit
boundaries. Fix this by handling the trailing pixels on each line
separately. The performance improvements in the original commit do not
regress by this change.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220313192952.12058-3-tzimmermann@suse.de

fbdev: Fix cfb_imageblit() for arbitrary image widths

Commit 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
broke cfb_imageblit() for image widths that are not aligned to 8-bit
boundaries. Fix this by handling the trailing pixels on each line
separately. The performance improvements in the original commit do not
regress by this change.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 0d03011894d2 ("fbdev: Improve performance of cfb_imageblit()")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220313192952.12058-3-tzimmermann@suse.de

fbdev: Improve performance of cfb_imageblit()

Improve the performance of cfb_imageblit() by manually unrolling
the inner blitting loop and moving some invariants out. The compiler
failed to do this automatically. This change keeps cfb_imageblit()
in sync with sys_imagebit().

A microbenchmark measures the average number of CPU cycles
for cfb_imageblit() after a stabilizing period of a few minutes
(i7-4790, FullHD, simpledrm, kernel with debugging).

cfb_imageblit(), new: 15724 cycles
cfb_imageblit(): old: 30566 cycles

In the optimized case, cfb_imageblit() is now ~2x faster than before.

v3:
* fix commit description (Pekka)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-5-tzimmermann@suse.de

fbdev: Remove trailing whitespaces from cfbimgblt.c

Fix coding style. No functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-4-tzimmermann@suse.de

fbdev: move fbdev core files to separate directory

Instead of having fbdev framework core files at the root fbdev
directory, mixed with random fbdev device drivers, move the fbdev core
files to a separate core directory. This makes it much clearer which of
the files are actually part of the fbdev framework, and which are part
of device drivers.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>