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Message-ID: <ZJG91zMQW3Rnvdbe@smile.fi.intel.com>
Date: Tue, 20 Jun 2023 17:55:19 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@...el.com>,
intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org,
Masahiro Yamada <masahiroy@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Kevin Brodsky <kevin.brodsky@....com>,
Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>
Subject: Re: [PATCH 2/3] linux/bits.h: Add fixed-width GENMASK and BIT macros
On Tue, Jun 20, 2023 at 05:47:34PM +0300, Jani Nikula wrote:
> On Thu, 15 Jun 2023, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> > On Fri, May 12, 2023 at 02:45:19PM +0300, Jani Nikula wrote:
> >> On Fri, 12 May 2023, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> >> > On Fri, May 12, 2023 at 02:25:18PM +0300, Jani Nikula wrote:
> >> >> On Fri, 12 May 2023, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> >> >> > On Mon, May 08, 2023 at 10:14:02PM -0700, Lucas De Marchi wrote:
> >> >> >> Add GENMASK_U32(), GENMASK_U16() and GENMASK_U8() macros to create
> >> >> >> masks for fixed-width types and also the corresponding BIT_U32(),
> >> >> >> BIT_U16() and BIT_U8().
> >> >> >
> >> >> > Why?
> >> >>
> >> >> The main reason is that GENMASK() and BIT() size varies for 32/64 bit
> >> >> builds.
> >> >
> >> > When needed GENMASK_ULL() can be used (with respective castings perhaps)
> >> > and BIT_ULL(), no?
> >>
> >> How does that help with making them the same 32-bit size on both 32 and
> >> 64 bit builds?
> >
> > u32 x = GENMASK();
> > u64 y = GENMASK_ULL();
> >
> > No? Then use in your code either x or y. Note that I assume that the parameters
> > to GENMASK*() are built-time constants. Is it the case for you?
>
> What's wrong with wanting to define macros with specific size, depending
> on e.g. hardware registers instead of build size?
Nothing, but I think the problem is smaller than it's presented.
And there are already header for bitfields with a lot of helpers
for (similar) cases if not yours.
> What would you use for printk format if you wanted to to print
> GENMASK()?
%lu, no?
--
With Best Regards,
Andy Shevchenko
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