netdev - Re: [PATCH 01/17] bitfield: Add non-constant field

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Message-ID: <637a4183861a1f2cdab52b7652bfa7ed33fbcdd2.camel@sipsolutions.net>
Date:   Tue, 23 Nov 2021 17:24:15 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Paul Walmsley <paul@...an.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Tero Kristo <kristo@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
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Subject: Re: [PATCH 01/17] bitfield: Add non-constant field_{prep,get}()
 helpers

On Tue, 2021-11-23 at 09:36 +0100, Geert Uytterhoeven wrote:


Ah, here's your comment wrt. which one is nicer :)

> > > We have the upper-case (constant) versions, and already
> > > {u32,...}_get_bits()/etc.
> 
> TBH, I don't like the *_get_bits() API: in general, u32_get_bits() does
> the same as FIELD_GET(), but the order of the parameters is different?

I don't really see how "the order of parameters is different" is a
downside? Yeah it means if you're used to FIELD_GET() then you'll
retrain, but ...?

> (*_replace_bits() seems to be useful, though)

Indeed.

Also as I said in my other mail, the le32/be32/... variants are
tremendously useful, and they fundamentally cannot be expressed with the
FIELD_GET() or field_get() macros. IMHO this is a clear advantage to the
typed versions, and if you ask me we should get rid of the FIELD_GETand
FIELD_PREP entirely - difficult now, but at least let's not propagate
that?

johannes