linux-kernel - Re: [PATCH v4 1/7] riscv: asm: alternative-macros: Introduce ALTERNATIVE

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Message-ID: <3217756.bB369e8A3T@diego>
Date:   Fri, 25 Nov 2022 11:20:04 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Conor Dooley <conor@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Guo Ren <guoren@...nel.org>,
        Jisheng Zhang <jszhang@...nel.org>,
        Atish Patra <atishp@...osinc.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-renesas-soc@...r.kernel.org,
        Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v4 1/7] riscv: asm: alternative-macros: Introduce ALTERNATIVE_3() macro

Am Freitag, 25. November 2022, 11:02:21 CET schrieb Lad, Prabhakar:
> Hi Heiko,
> 
> On Thu, Nov 24, 2022 at 7:58 PM Heiko Stübner <heiko@...ech.de> wrote:
> >
> > Am Donnerstag, 24. November 2022, 20:52:33 CET schrieb Conor Dooley:
> > > On Thu, Nov 24, 2022 at 05:22:01PM +0000, Prabhakar wrote:
> > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > >
> > > > Introduce ALTERNATIVE_3() macro.
> > >
> > > Bit perfunctory I think! There's a lovely comment down below that would
> > > make for a better commit message if you were to yoink it.
> > > Content looks about what I'd expect to see though.
> >
> > Also both the comment on the original ALTERNATIVE_2 and the new ALTERNATIVE_3
> > should probably be merged into a single comment explaining this once for all
> > ALTERNATIVE_x variants.
> >
> > Especially with the dma stuff, I'm pretty sure we'll get at least an ALTERNATIVE_4
> > if not even more ;-) . So we defnitly don't want to repeat this multiple times.
> >
> Do agree. How about the below?
> 
> /*
>  * Similar to what ALTERNATIVE_2() macro does but with an additional
>  * vendor content.
>  */
> 
> So the other ALTERNATIVE_2+() macros will keep on building on it.

My idea was more like having _one_ comment block of something like

-----
/*
 * ALTERNATIVE_x macros allow providing multiple replacement options
 * for an ALTERNATIVE code section. This is helpful if multiple
 * implementation variants for the same functionality exist for
 * different cpu cores.
 *
 * Usage:
 *   ALTERNATIVE_x(old_content,
 *	new_content1, vendor_id1, errata_id1, CONFIG_k1,
 *	new_content2, vendor_id2, errata_id2, CONFIG_k2,
 *	...
 *	new_contentx, vendor_idx, errata_idx, CONFIG_kx)
 */

#define ALTERNATIVE_2(...)
#define ALTERNATIVE_3(...)
etc
-----

So this would include dropping the old comment over ALTERNATIVE2


Heiko