[-next,v2] dmaengine: mcf-edma: fix x86_64 allmodconfig compilation warning

[Angelo Dureghello <angelo@sysam.it>]

Hi Geert,

On Fri, Sep 14, 2018 at 02:13:50PM +0200, Angelo Dureghello wrote:
> Hi Geert,
> 
> On Fri, Sep 14, 2018 at 01:35:22PM +0200, Geert Uytterhoeven wrote:
> > Hi Angelo,
> > 
> > Thanks for your patch!
> > 
> > On Fri, Sep 14, 2018 at 9:12 AM Angelo Dureghello <angelo@sysam.it> wrote:
> > > This patch fixes the compilation warning reported
> > > during x86_64 allmodconfig build.
> > 
> > Please quote the warning, so people know what it is about:
> > 
> >     drivers/dma/mcf-edma.c: In function 'mcf_edma_filter_fn':
> >     drivers/dma/mcf-edma.c:296:33: warning: cast from pointer to
> > integer of different size [-Wpointer-to-int-cast]
> >        return (mcf_chan->slave_id == (u32)param);
> > 
> 
> Ok done.
> 
> > > Reported-By: Stephen Rothwell <sfr@canb.auug.org.au>
> > > Signed-off-by: Angelo Dureghello <angelo@sysam.it>
> > > ---
> > > Changes for v2:
> > >   - added Reported-By
> > > ---
> > >  drivers/dma/mcf-edma.c                     | 3 ++-
> > >  include/linux/platform_data/dma-mcf-edma.h | 2 +-
> > >  2 files changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/dma/mcf-edma.c b/drivers/dma/mcf-edma.c
> > > index 4d30d5302649..e08e2409a102 100644
> > > --- a/drivers/dma/mcf-edma.c
> > > +++ b/drivers/dma/mcf-edma.c
> > > @@ -292,8 +292,9 @@ bool mcf_edma_filter_fn(struct dma_chan *chan, void *param)
> > >  {
> > >         if (chan->device->dev->driver == &mcf_edma_driver.driver) {
> > >                 struct fsl_edma_chan *mcf_chan = to_fsl_edma_chan(chan);
> > > +               unsigned int req = *(unsigned int *)param;
> > 
> > This looks a bit hackish to me.
> > >
> > > -               return (mcf_chan->slave_id == (u32)param);
> > 
> > The recommended way to cast from pointers to integers is to
> > use uintptr_t, which always has the same size as a pointer, i.e.:
> > 
> 
> slave_id is acually an u32. So, if i understsand, when compiled
> on x86_64 using uintptr_t, the cast should trigger the same issue. 
> I preferred, as i.e. ti/omap dma driver is doing, to simply 
> use a pointer to an int (int[]) as passed type in param,
> so i can then indirectly access the integer. I tested
> proper functionality in ColdFire and that there are no warnings
> anymore in both ColdFire and x86_64 allmodconfig so the patch,
> hopefully, should be legal.  
> 
I misunderstood uintptr_t, verified now that it works fine
for this case, reducing the patch to a single line change.
So switching to it. Thanks !

> >         return (mcf_chan->slave_id == (uintptr_t)param);
> > 
> > > +               return (mcf_chan->slave_id == req);
> > >         }
> > >
> > >         return false;
> > > diff --git a/include/linux/platform_data/dma-mcf-edma.h b/include/linux/platform_data/dma-mcf-edma.h
> > > index d718ccfa3421..97cb79bda646 100644
> > > --- a/include/linux/platform_data/dma-mcf-edma.h
> > > +++ b/include/linux/platform_data/dma-mcf-edma.h
> > > @@ -21,7 +21,7 @@ struct dma_slave_map;
> > >
> > >  bool mcf_edma_filter_fn(struct dma_chan *chan, void *param);
> > >
> > > -#define MCF_EDMA_FILTER_PARAM(ch)      ((void *)ch)
> > > +#define MCF_EDMA_FILTER_PARAM(ch)      ((int[]) { (ch) })
> > >
> > >  /**
> > >   * struct mcf_edma_platform_data - platform specific data for eDMA engine
> > 
> > Gr{oetje,eeting}s,
> > 
> >                         Geert
> > 
> Regards,
> Angelo
> 
> > -- 
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> > 
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds

Regards,
Angelo