linux-kernel - Re: [PATCH 0/5] fbdev: Move framebuffer I/O helpers to <asm/fb.h>

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Date:   Wed, 26 Apr 2023 21:21:10 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     deller@....de, geert@...ux-m68k.org, javierm@...hat.com,
        daniel@...ll.ch, vgupta@...nel.org, chenhuacai@...nel.org,
        kernel@...0n.name, davem@...emloft.net,
        James.Bottomley@...senpartnership.com, arnd@...db.de,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-arch@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org,
        loongarch@...ts.linux.dev, linux-m68k@...ts.linux-m68k.org,
        sparclinux@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-parisc@...r.kernel.org
Subject: Re: [PATCH 0/5] fbdev: Move framebuffer I/O helpers to <asm/fb.h>

Hi Thomas.

On Wed, Apr 26, 2023 at 03:04:15PM +0200, Thomas Zimmermann wrote:
> Fbdev provides helpers for framebuffer I/O, such as fb_readl(),
> fb_writel() or fb_memcpy_to_fb(). The implementation of each helper
> depends on the architecture. It's still all located in fbdev's main
> header file <linux/fb.h>. Move all of it into each archtecture's
> <asm/fb.h>, with shared code in <asm-generic/fb.h>.

For once I think this cleanup is moving things in the wrong direction.

The fb_* helpers predates the generic io.h support and try to
add a generic layer for read read / write operations.

The right fix would be to migrate fb_* to use the io helpers
we have today - so we use the existing way to handle the architecture
specific details.

>From a quick look there seems to be some challenges but the current
helpers that re-do part of io.h is not the way forward and hiding them
in arch/include/asm/fb.h seems counter productive.

	Sam