Re: [PATCH v2 5/5] fbdev: Define framebuffer I/O from Linux' I/O functions

Thomas Zimmermann <tzimmermann@xxxxxxx> · Fri, 28 Apr 2023 16:18:38 +0200

Hi

Am 28.04.23 um 15:12 schrieb Sam Ravnborg:

Hi Thomas,

On Fri, Apr 28, 2023 at 11:27:11AM +0200, Thomas Zimmermann wrote:

Implement framebuffer I/O helpers, such as fb_read*() and fb_write*()
with Linux' regular I/O functions. Remove all ifdef cases for the
various architectures.

Most of the supported architectures use __raw_() I/O functions or treat
framebuffer memory like regular memory. This is also implemented by the
architectures' I/O function, so we can use them instead.

Sparc uses SBus to connect to framebuffer devices. It provides respective
implementations of the framebuffer I/O helpers. The involved sbus_()
I/O helpers map to the same code as Sparc's regular I/O functions. As
with other platforms, we can use those instead.

We leave a TODO item to replace all fb_() functions with their regular
I/O counterparts throughout the fbdev drivers.

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
  include/linux/fb.h | 63 +++++++++++-----------------------------------
  1 file changed, 15 insertions(+), 48 deletions(-)

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 08cb47da71f8..4aa9e90edd17 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -15,7 +15,6 @@
  #include <linux/list.h>
  #include <linux/backlight.h>
  #include <linux/slab.h>
-#include <asm/io.h>

  

  struct vm_area_struct;

  struct fb_info;
@@ -511,58 +510,26 @@ struct fb_info {
   */
  #define STUPID_ACCELF_TEXT_SHIT

  

-// This will go away

-#if defined(__sparc__)
-
-/* We map all of our framebuffers such that big-endian accesses
- * are what we want, so the following is sufficient.
+/*
+ * TODO: Update fbdev drivers to call the I/O helpers directly and
+ *       remove the fb_() tokens.
   */

When the __raw_* variants are used, as Geert points out, then I think
the memcpy / memset can be replaced, but the rest seems fine to keep.



I'd either want the regular I/O functions or the fb_() wrappers, but not 

the __raw_() function. I'd also prefer to keep fb_ in front of memset 

and memcpy.  I'd be happy to have fb_() wrappers that are I/O helpers 

without ordering guarantees. I'd just wouldn't want them in <linux/fb.h>


Best regards
Thomas



My personal opinion is that __raw_* is for macro use etc, and not
something to use everywhere. So I like the fb_read/fb_write macros.
But that is just my color of the bikeshed.

	Sam


--
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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