Re: [PATCH v3 4/6] fbdev: Include <linux/io.h> via <asm/fb.h>

From
Thomas Zimmermann <tzimmermann@suse.de>
Date
2023-05-03 08:13:09
Also in
dri-devel, linux-arch, linux-arm-kernel, linux-m68k, lkml, loongarch, sparclinux
Reply to
Javier Martinez Canillas, 2023-05-03
Hi

Am 03.05.23 um 09:19 schrieb Javier Martinez Canillas:
Thomas Zimmermann [off-list ref] writes:

Hello Thomas,
quoted
Am 02.05.23 um 21:54 schrieb Sam Ravnborg:
quoted
On Tue, May 02, 2023 at 03:02:21PM +0200, Thomas Zimmermann wrote:
[...]
quoted
quoted
quoted
   #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.
Where did youher this? I only know about this in the case of asm/io.h
vs. linux/io.h.
I understand that's the case too. I believe even checkpatch.pl complains
about it? (not that the script always get right, but just as an example).
Do you know if that's the general rule? If so, we might want to repurpose <asm/fbio.h> for the framebuffer I/O functions.

Best regards
Thomas
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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