BT.601 weights RGB components by certain factors to convert the
color to grayscale. Normalize the constants to 256 instead of 10.
Allows for slightly more precise rounding. The division by 256 can
be compiled as an 8-bit shift, which might be faster on some hardware.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250603161158.423962-1-tzimmermann@suse.de
Add drm_fb_xfrm_line_32to8() to implement conversion from 32-bit
pixels to 8-bit pixels. The pixel-conversion is specified by the
given callback parameter. Mark the helper as always_inline to avoid
overhead from function calls.
Then implement all existing line-conversion functions with the new
generic call and the respective pixel-conversion helper.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-6-tzimmermann@suse.de
Add drm_fb_xfrm_line_32to16() to implement conversion from 32-bit
pixels to 16-bit pixels. The pixel-conversion is specified by the
given callback parameter. Mark the helper as always_inline to avoid
overhead from function calls.
Then implement all existing line-conversion functions with the new
generic call and the respective pixel-conversion helper. There's one
pixel-conversion helper that swaps output bytes. It is for gud and
requires refactoring, so don't move it into the header file.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-5-tzimmermann@suse.de
Add drm_fb_xfrm_line_32to24() to implement conversion from 32-bit
pixels to 24-bit pixels. The pixel-conversion is specified by the
given callback parameter. Mark the helper as always_inline to avoid
overhead from function calls.
Then implement all existing line-conversion functions with the new
generic call and the respective pixel-conversion helper.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-4-tzimmermann@suse.de
The DRM draw helpers contain format-conversion helpers that operate
on individual pixels. Move them into an internal header file and adopt
them as individual API. Update the draw code accordingly. The pixel
helpers will also be useful for other format conversion helpers.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-2-tzimmermann@suse.de
