Subject: Re: [PATCH] net: hix5hd2_gmac: avoid integer overload warning

From: Joe Perches <[email-masked]>
Date: Fri, 16 Oct 2015 11:04:14 -0700

On Fri, 2015-10-16 at 13:28 +0200, Arnd Bergmann wrote:
> On Friday 16 October 2015 11:14:44 David Laight wrote:
> > From: Arnd Bergmann
> > > Sent: 16 October 2015 11:01
> > > BITS_RX_EN is an 'unsigned long' constant, so the ones complement of that
> > > has bits set that do not fit into a 32-bit variable on 64-bit architectures,
> > > which causes a harmless gcc warning:
> > ...
> > >  static void hix5hd2_port_disable(struct hix5hd2_priv *priv)
> > >  {
> > > -     writel_relaxed(~(BITS_RX_EN | BITS_TX_EN), priv->base + PORT_EN);
> > > +     writel_relaxed(~(u32)(BITS_RX_EN | BITS_TX_EN), priv->base + PORT_EN);
> > >       writel_relaxed(0, priv->base + DESC_WR_RD_ENA);
> > 
> > ISTM that just means that the constants shouldn't be 'long'.
> 
> Right, but that would probably mean changing the BIT() macro or not using it
> here. In the past I've argued against using that macro, but I've given
> up that fight.

Fight on... (Somebody must have gone to USC here)

There might be value in a BIT_U32 macro.
Maybe BIT_U64 too.