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

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Thomas Zimmermann <tzimmermann@xxxxxxx> writes:

Hello Thomas,

Am 02.05.23 um 21:54 schrieb Sam Ravnborg:
On Tue, May 02, 2023 at 03:02:21PM +0200, Thomas Zimmermann wrote:

[...]

  #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).

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat




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