Den 20.04.2016 19:44, skrev Daniel Vetter:
On Wed, Apr 20, 2016 at 05:25:26PM +0200, 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.
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);
Hm, do we need pgpropt_writecombine? There recently was some discussion
(on the arc platform) that fbdev pgprots need to be fixed up in fbdev
code. I have no idea, just repeating from memory ...
I need it or else I get partial lines that doesn't get updated on the
display.
fbdev code that doesn't set (struct fb_ops *)->fb_mmap, gets this for free
in the default fb_mmap implementation (drivers/video/fbdev/core/fbmem.c).
It calls fb_pgprotect() at the end which 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 here 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.
I think the case you refer to was solved with using fb_pgprotect() for
the platform in question and it didn't involve deferred io.
-Daniel
return 0;
}
Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
---
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 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,
--
2.2.2
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