[U-Boot] [PATCH v2 1/2] linux/bitops.h: Add BIT macro

[Tom Rini]

On Wed, Apr 29, 2015 at 06:33:41PM -0600, Simon Glass wrote:
> Hi Jagan,
> 
> On 29 April 2015 at 08:58, Jagan Teki <jagannadh.teki at gmail.com> wrote:
> > Hi Simon,
> >
> > On 29 April 2015 at 20:12, Simon Glass <sjg at chromium.org> wrote:
> >> Hi Tom,
> >>
> >> On 29 April 2015 at 07:08, Tom Rini <trini at konsulko.com> wrote:
> >>> On Wed, Apr 29, 2015 at 05:35:05PM +0530, Jagannadha Sutradharudu Teki wrote:
> >>>
> >>>> Replace (1 << nr) to BIT(nr) where nr = 0, 1, 2 .... 31
> >>>>
> >>>> Signed-off-by: Jagannadha Sutradharudu Teki <jagannadh.teki at gmail.com>
> >>>> Cc: Masahiro Yamada <yamada.m at jp.panasonic.com>
> >>>> Cc: Tom Rini <trini at konsulko.com>
> >>>> Cc: Simon Glass <sjg at chromium.org>
> >>>
> >>> I think that conceptually this is a good idea.  We need to apply this
> >>> fairly quickly however as it already throws out a few rejects with the
> >>> PRs I've taken and doing some local testing on.
> >>
> >> We have to date avoided this (I've been here before). But I think it
> >> is useful. One concern I have is misuse, when someone does BIT(0) |
> >> BIT(1))| BIT(2) | BIT(3) instead of 0xf, for example.
> >
> > Probably we can achieve this with GENMASK(h, l), may be we can add that also?
> 
> I'm not sure about that...we might end up with this:
> 
> http://patchwork.ozlabs.org/patch/93363/

Welcome to the world of introducing an idea before the rest of the
community is ready :( .  GENMASK as Jagan is talking about came into the
kernel (well, into <linux/bitops.h> in 2013.  So yeah, we could pull
that macro in too and clean up as needed / ensure people don't do funny
looking things like BIT(1) | BIT(2) | ... 

-- 
Tom
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