Hi Robin, Geert Am 28.04.23 um 14:27 schrieb Geert Uytterhoeven:
On Fri, Apr 28, 2023 at 2:18 PM Robin Murphy <robin.murphy@xxxxxxx> wrote:On 2023-04-28 10:27, 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. */ - -// This will go away -#define fb_readb sbus_readb -#define fb_readw sbus_readw -#define fb_readl sbus_readl -#define fb_readq sbus_readq -#define fb_writeb sbus_writeb -#define fb_writew sbus_writew -#define fb_writel sbus_writel -#define fb_writeq sbus_writeq -#define fb_memset sbus_memset_io -#define fb_memcpy_fromfb sbus_memcpy_fromio -#define fb_memcpy_tofb sbus_memcpy_toio - -#elif defined(__i386__) || defined(__alpha__) || defined(__x86_64__) || \ - defined(__hppa__) || defined(__sh__) || defined(__powerpc__) || \ - defined(__arm__) || defined(__aarch64__) || defined(__mips__) - -#define fb_readb __raw_readb -#define fb_readw __raw_readw -#define fb_readl __raw_readl -#define fb_readq __raw_readq -#define fb_writeb __raw_writeb -#define fb_writew __raw_writew -#define fb_writel __raw_writel -#define fb_writeq __raw_writeqNote that on at least some architectures, the __raw variants are native-endian, whereas the regular accessors are explicitly little-endian, so there is a slight risk of inadvertently changing behaviour on big-endian systems (MIPS most likely, but a few old ARM platforms run BE as well).Also on m68k, when ISA or PCI are enabled. In addition, the non-raw variants may do some extras to guarantee ordering, which you do not need on a frame buffer. So I'd go for the __raw_*() variants everywhere.
Ok, makes sense. But it also means that we won't be able to remove the fb_() helpers. If we go with this proposal, I'll add your comments to the header file, so it's clear why they're still there.
Best regards Thomas
Gr{oetje,eeting}s,
Geert
-- 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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