netdev - Re: [PATCH 09/12] m68k: use the coherent DMA code for coldfire without data cache

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Message-ID: <CAMuHMdVq0ihLthVQF-2v4_E=m7jdOZty8b69eizJyWoU+0CFCw@mail.gmail.com>
Date: Tue, 17 Oct 2023 10:40:32 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Christoph Hellwig <hch@....de>
Cc: Greg Ungerer <gerg@...ux-m68k.org>, iommu@...ts.linux.dev, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Conor Dooley <conor@...nel.org>, Magnus Damm <magnus.damm@...il.com>, 
	Robin Murphy <robin.murphy@....com>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Wei Fang <wei.fang@....com>, Shenwei Wang <shenwei.wang@....com>, 
	Clark Wang <xiaoning.wang@....com>, NXP Linux Team <linux-imx@....com>, 
	linux-m68k@...ts.linux-m68k.org, netdev@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, linux-renesas-soc@...r.kernel.org, 
	Jim Quinlan <james.quinlan@...adcom.com>
Subject: Re: [PATCH 09/12] m68k: use the coherent DMA code for coldfire
 without data cache

On Mon, Oct 16, 2023 at 7:48 AM Christoph Hellwig <hch@....de> wrote:
> Coldfire cores configured without a data cache are DMA coherent and
> should thus simply use the simple coherent version of dma-direct.
>
> Introduce a new COLDFIRE_COHERENT_DMA Kconfig symbol as a convenient
> short hand for such configurations, and a M68K_NONCOHERENT_DMA symbol
> for all cases where we need to build non-coherent DMA infrastructure
> to simplify the Kconfig and code conditionals.
>
> Not building the non-coherent DMA code slightly reduces the code
> size for such configurations.
>
> Numers for m5249evb_defconfig below:
>
>   text     data     bss     dec     hex filename
> 2896158  401052   65392 3362602  334f2a vmlinux.before
> 2895166  400988   65392 3361546  334b0a vmlinux.after
>
> Signed-off-by: Christoph Hellwig <hch@....de>

The m68kclassic-with-MMU parts look fine to me, so
Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org>

I'll defer to Greg for the nommu and Coldfire parts...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds