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arc: Add our own implementation of fb_pgprotect()

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During mmaping of frame-buffer pages to user-space
fb_protect() is called to set proper page settings.

In case of ARC we need to mark pages that are mmaped to
user as uncached because of 2 reasons:
 * Huge amount of data if passing through data cache will
   thrash cache a lot making cache almost useless for other
   less traffic hungry processes.
 * Data written by user in FB will be immediately available for
   hardware (such as PGU etc) without requirements to flush data
   cache regularly.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Alexey Brodkin 2016-03-28 14:36:38 +03:00 committed by Vineet Gupta
parent 732dc97bae
commit e5e0a65cd2
1 changed files with 19 additions and 0 deletions
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19
arch/arc/include/asm/fb.h Normal file
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#ifndef _ASM_FB_H_
#define _ASM_FB_H_
#include <linux/fb.h>
#include <linux/fs.h>
#include <asm/page.h>
static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
unsigned long off)
{
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
}
static inline int fb_is_primary_device(struct fb_info *info)
{
return 0;
}
#endif /* _ASM_FB_H_ */