From ba0263340a2aeaf5f08e4f2b0f4c29e300828b06 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Noralf=20Tr=C3=B8nnes?= Date: Thu, 28 Apr 2016 17:18:34 +0200 Subject: [PATCH] fbdev: fb_defio: Export fb_deferred_io_mmap MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Acked-by: Tomi Valkeinen Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1461856717-6476-5-git-send-email-noralf@tronnes.org --- drivers/video/fbdev/core/fb_defio.c | 3 ++- include/linux/fb.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index 57721c73177f..74b5bcac8bf2 100644 --- a/drivers/video/fbdev/core/fb_defio.c +++ b/drivers/video/fbdev/core/fb_defio.c @@ -164,7 +164,7 @@ static const struct address_space_operations fb_deferred_io_aops = { .set_page_dirty = fb_deferred_io_set_page_dirty, }; -static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) +int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) { vma->vm_ops = &fb_deferred_io_vm_ops; vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; @@ -173,6 +173,7 @@ static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) vma->vm_private_data = info; return 0; } +EXPORT_SYMBOL(fb_deferred_io_mmap); /* workqueue callback */ static void fb_deferred_io_work(struct work_struct *work) diff --git a/include/linux/fb.h b/include/linux/fb.h index dfe88351341f..a964d076b4dc 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -673,6 +673,7 @@ static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch, } /* drivers/video/fb_defio.c */ +int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma); extern void fb_deferred_io_init(struct fb_info *info); extern void fb_deferred_io_open(struct fb_info *info, struct inode *inode, -- 2.20.1