Re: [PATCH V7 1/2] csky/dma: bugfix dma_sync_for_cpu/device

[Guo Ren]

On Mon, Sep 24, 2018 at 10:38:04PM +0200, Arnd Bergmann wrote:
> On Tue, Sep 18, 2018 at 3:48 PM Guo Ren <ren_guo@xxxxxxxxx> wrote:
> >
> > ref: https://lkml.org/lkml/2018/5/18/1068
> >
> >         map             for_cpu         for_device      unmap
> > TO_DEV  writeback       none            writeback       none
> > TO_CPU  invalidate      invalidate*     invalidate      invalidate*
> > BIDIR   writeback       invalidate      writeback       invalidate
> >
> > Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx>
> 
> Same comment as for the other patch: Explain why the original
> version is wrong first. When giving a reference to some other
> discussion, use the "Link" tag above your Signed-off-by line.
> To point to a discussion on lkml, lore.kernel.org is the
> recommended archive, so it would become
> 
> Link: https://lore.kernel.org/lkml/20180518215548.GH17671@xxxxxxxxxxxxxxxxxxxxx/
Ok, I'll improve the comment:

Fixup dma_mapping error in linux-4.19-rc3, and we must implement all
DMA_TO_DEVICE/FROM_DEVICE/BIDIRECTIONAL for both sync_dma_for_device/cpu.
The implementation of arch should follow the following rules:

         map             for_cpu         for_device      unmap
 TO_DEV  writeback       none            writeback       none
 TO_CPU  invalidate      invalidate*     invalidate      invalidate*
 BIDIR   writeback       invalidate      writeback       invalidate

 Link: https://lore.kernel.org/lkml/20180518215548.GH17671@xxxxxxxxxxxxxxxxxxxxx/
 Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx>

Best Regards
 Guo Ren