On 28/04/16 18:18, Noralf Trønnes wrote:
Export fb_deferred_io_mmap so drivers can change vma->vm_page_prot. When the framebuffer memory is allocated using dma_alloc_writecombine() instead of vmalloc(), I get cache syncing problems on ARM. This solves it:
static int drm_fbdev_cma_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) { fb_deferred_io_mmap(info, vma); vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
return 0; }
Could this have been done in the core? Drivers that don't set (struct fb_ops *)->fb_mmap, gets a call to fb_pgprotect() at the end of the default fb_mmap implementation (drivers/video/fbdev/core/fbmem.c). This is an architecture specific function that on many platforms uses pgprot_writecombine(), but not on all. And looking at some of the fb_mmap implementations, some of them sets vm_page_prot to nocache for instance, so I think the safest bet is to do this in the driver and not in the fbdev core. And we can't call fb_pgprotect() from fb_deferred_io_mmap() either because we don't have access to the file pointer that powerpc needs.
Signed-off-by: Noralf Trønnes noralf@tronnes.org
Acked-by: Tomi Valkeinen tomi.valkeinen@ti.com
Tomi