On Sun, Sep 11, 2022 at 09:12:44AM +0200, Nam Cao wrote:
> On Fri, Sep 9, 2022 at 8:03 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Fri, Sep 09, 2022 at 02:17:55PM +0200, Nam Cao wrote:
> > > Remove volatile qualifier for the member rd0 of struct vnt_rx_desc,
> > > because there is no reason it must be volatile.
> > >
> > > Signed-off-by: Nam Cao <namcaov@xxxxxxxxx>
> > > ---
> > > drivers/staging/vt6655/desc.h | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/staging/vt6655/desc.h b/drivers/staging/vt6655/desc.h
> > > index 17a40c53b8ff..3f0f287b1693 100644
> > > --- a/drivers/staging/vt6655/desc.h
> > > +++ b/drivers/staging/vt6655/desc.h
> > > @@ -182,7 +182,7 @@ struct vnt_rdes1 {
> > >
> > > /* Rx descriptor*/
> > > struct vnt_rx_desc {
> > > - volatile struct vnt_rdes0 rd0;
> > > + struct vnt_rdes0 rd0;
> >
> > You can not just remove this without describing _WHY_ it is ok to do so.
> >
> > Have you properly determined why it is, or is not, ok to use volatile
> > here?
>
> I did not carefully look at the volatile usage here. After looking at it
> again, using volatile is actually valid: the structure resides on coherent
> memory.
Are you sure? That's a very odd thing for a driver to need. Looks like
they are allocating some dma memory and then pointing structures on top
of that memory. Why would you need to have "volatile" markings on a
structure definition for that?
Dig into this some more please, I don't think this is correct.
thanks,
greg k-h
