MFC r306555:

Provide way for framebuffer driver to request mmap(2) mapping type

On ARM if memattr is not overriden mmap(2) maps framebuffer
memory as WBWA which means part of changes to content in userland
end up in cache and appear on screen gradually as cache lines are
evicted. This change adds configurable memattr that hardware fb
implementation can set to get the memory mapping type it
requires:

- Add new flag FB_FLAG_MEMATTR that indicates that framebuffer
    driver overrides default memattr
- Add new field fb_memattr to struct fb_info to specify requested
    memattr

Reviewed by:	ray
Differential Revision:	https://reviews.freebsd.org/D8064

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/sys/fbio.h b/sys/sys/fbio.h
index 17cd891..b077906 100644
--- a/sys/sys/fbio.h
+++ b/sys/sys/fbio.h
@@ -142,6 +142,8 @@ struct fb_info {
 	uint32_t	fb_flags;
 #define	FB_FLAG_NOMMAP		1	/* mmap unsupported. */
 #define	FB_FLAG_NOWRITE		2	/* disable writes for the time being */
+#define	FB_FLAG_MEMATTR		4	/* override memattr for mmap */
+	vm_memattr_t	fb_memattr;
 	int		fb_stride;
 	int		fb_bpp;		/* bits per pixel */
 	uint32_t	fb_cmap[16];