On Thu, Apr 6, 2023, at 16:30, Thomas Zimmermann wrote:

+
 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);
 }
+#define fb_pgprotect fb_pgprotect

I still feel that for architectures like arc that don't have
pgprot_writecombine(), it would b best to go with the
generic implementation that currently behaves the exact
same way. If pgprot_writecombine() gets added in the future,
it would cause the architecture to behave as expected rather
than introducing the same bug that mips has.

      Arnd