Hi Christoph, > On Tue, Sep 29, 2020 at 04:44:25PM +0800, Sherry Sun wrote: > > Mapping kernel space memory to user space as noncached, since user > > space need check the updates of avail_idx and device page flags timely. > > > > Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx> > > Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx> > > --- > > drivers/misc/mic/vop/vop_vringh.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/misc/mic/vop/vop_vringh.c > > b/drivers/misc/mic/vop/vop_vringh.c > > index 4d5feb39aeb7..6e193bd64ef1 100644 > > --- a/drivers/misc/mic/vop/vop_vringh.c > > +++ b/drivers/misc/mic/vop/vop_vringh.c > > @@ -1057,7 +1057,7 @@ static int vop_mmap(struct file *f, struct > vm_area_struct *vma) > > } > > err = remap_pfn_range(vma, vma->vm_start + offset, > > pa >> PAGE_SHIFT, size, > > - vma->vm_page_prot); > > + pgprot_noncached(vma->vm_page_prot)); > > You can't call remap_pfn_range on memory returned from > dma_alloc_coherent (which btw is not marked uncached on many platforms). > > You need to use the dma_mmap_coherent helper instead. And this also > needs to go into the first patch. Okay, will try to use dma_mmap_coherent api in V3. Thanks. Regards Sherry
