From: Sam Ravnborg <sam@ravnborg.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: deller@gmx.de, geert@linux-m68k.org, javierm@redhat.com,
daniel@ffwll.ch, vgupta@kernel.org, chenhuacai@kernel.org,
kernel@xen0n.name, davem@davemloft.net,
James.Bottomley@hansenpartnership.com, arnd@arndb.de,
linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-arch@vger.kernel.org, linux-snps-arc@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org,
sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org
Subject: Re: [PATCH v3 4/6] fbdev: Include <linux/io.h> via <asm/fb.h>
Date: Tue, 2 May 2023 21:54:29 +0200 [thread overview]
Message-ID: <20230502195429.GA319489@ravnborg.org> (raw)
In-Reply-To: <20230502130223.14719-5-tzimmermann@suse.de>
Hi Thomas,
On Tue, May 02, 2023 at 03:02:21PM +0200, Thomas Zimmermann wrote:
> Fbdev's main header file, <linux/fb.h>, includes <asm/io.h> to get
> declarations for I/O helper functions. From these declarations, it
> later defines framebuffer I/O helpers, such as fb_{read,write}[bwlq]()
> or fb_memset().
>
> The framebuffer I/O helpers depend on the system architecture and
> will therefore be moved into <asm/fb.h>. Prepare this change by first
> adding an include statement for <linux/io.h> to <asm-generic/fb.h>.
> Include <asm/fb.h> in all source files that use the framebuffer I/O
> helpers, so that they still get the necessary I/O functions.
>
...
>
> diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c
> index 60a96fdb5dd8..fd38e8a073b8 100644
> --- a/drivers/video/fbdev/arkfb.c
> +++ b/drivers/video/fbdev/arkfb.c
> @@ -27,6 +27,8 @@
> #include <linux/console.h> /* Why should fb driver call console functions? because console_lock() */
> #include <video/vga.h>
>
> +#include <asm/fb.h>
When we have a header like linux/fb.h - it is my understanding that it is
preferred to include that file, and not the asm/fb.h variant.
This is assuming the linux/fb.h contains the generic stuff, and includes
asm/fb.h for the architecture specific parts.
So drivers will include linux/fb.h and then they automatically get the
architecture specific parts from asm/fb.h.
In other words, drivers are not supposed to include asm/fb.h, if
linux.fb.h exists - and linux/fb.h shall include the asm/fb.h.
If the above holds true, then it is wrong and not needed to add asm/fb.h
as seen above.
There are countless examples where the above are not followed,
but to my best understanding the above it the preferred way to do it.
Sam
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next prev parent reply other threads:[~2023-05-02 19:54 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-02 13:02 [PATCH v3 0/6] fbdev: Move framebuffer I/O helpers to <asm/fb.h> Thomas Zimmermann
2023-05-02 13:02 ` [PATCH v3 1/6] fbdev/matrox: Remove trailing whitespaces Thomas Zimmermann
2023-05-02 13:02 ` [PATCH v3 2/6] ipu-v3: Include <linux/io.h> Thomas Zimmermann
2023-05-02 13:02 ` [PATCH v3 3/6] fbdev: Include <linux/io.h> in various drivers Thomas Zimmermann
2023-05-02 13:02 ` [PATCH v3 4/6] fbdev: Include <linux/io.h> via <asm/fb.h> Thomas Zimmermann
2023-05-02 19:54 ` Sam Ravnborg [this message]
2023-05-03 7:09 ` Thomas Zimmermann
2023-05-03 7:19 ` Javier Martinez Canillas
2023-05-03 8:09 ` Geert Uytterhoeven
2023-05-03 8:12 ` Thomas Zimmermann
2023-05-03 8:52 ` Arnd Bergmann
2023-05-02 13:02 ` [PATCH v3 5/6] fbdev: Move framebuffer I/O helpers into <asm/fb.h> Thomas Zimmermann
2023-05-02 20:03 ` Sam Ravnborg
2023-05-03 6:58 ` Thomas Zimmermann
2023-05-03 19:03 ` Sam Ravnborg
2023-05-02 20:06 ` Arnd Bergmann
2023-05-03 14:55 ` Thomas Zimmermann
2023-05-03 15:06 ` Arnd Bergmann
2023-05-02 13:02 ` [PATCH v3 6/6] fbdev: Rename fb_mem*() helpers Thomas Zimmermann
2023-05-02 20:08 ` Sam Ravnborg
2023-05-03 8:15 ` Thomas Zimmermann
2023-05-03 19:06 ` Sam Ravnborg
2023-05-03 8:21 ` [PATCH v3 0/6] fbdev: Move framebuffer I/O helpers to <asm/fb.h> Geert Uytterhoeven
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