| Message ID | 1461856717-6476-5-git-send-email-noralf@tronnes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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
diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c index 57721c7..74b5bca 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 dfe8835..a964d07 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,
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> --- Changes since v1: - Expand commit message drivers/video/fbdev/core/fb_defio.c | 3 ++- include/linux/fb.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) -- 2.2.2