Hi Thomas, On Tue, May 02, 2023 at 03:02:22PM +0200, Thomas Zimmermann wrote: > Implement framebuffer I/O helpers, such as fb_read*() and fb_write*(), > in the architecture's <asm/fb.h> header file or the generic one. In reality they are now all implemented in the generic one. > > The common case has been the use of regular I/O functions, such as > __raw_readb() or memset_io(). A few architectures used plain system- > memory reads and writes. Sparc used helpers for its SBus. > > The architectures that used special cases provide the same code in > their __raw_*() I/O helpers. So the patch replaces this code with the > __raw_*() functions and moves it to <asm-generic/fb.h> for all > architectures. Which is also documented here. > > v3: > * implement all architectures with generic helpers > * support reordering and native byte order (Geert, Arnd) > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > --- > include/asm-generic/fb.h | 101 +++++++++++++++++++++++++++++++++++++++ > include/linux/fb.h | 53 -------------------- > 2 files changed, 101 insertions(+), 53 deletions(-) > > diff --git a/include/asm-generic/fb.h b/include/asm-generic/fb.h > index 6922dd248c51..0540eccdbeca 100644 > --- a/include/asm-generic/fb.h > +++ b/include/asm-generic/fb.h > @@ -31,4 +31,105 @@ static inline int fb_is_primary_device(struct fb_info *info) > } > #endif > > +/* > + * I/O helpers for the framebuffer. Prefer these functions over their > + * regular counterparts. The regular I/O functions provide in-order > + * access and swap bytes to/from little-endian ordering. Neither is > + * required for framebuffers. Instead, the helpers read and write > + * raw framebuffer data. Independent operations can be reordered for > + * improved performance. > + */ > + > +#ifndef fb_readb > +static inline u8 fb_readb(const volatile void __iomem *addr) > +{ > + return __raw_readb(addr); > +} > +#define fb_readb fb_readb > +#endif When we need to provide an architecture specific variant the #ifndef foo ... #define foo foo can be added. Right now it is just noise as no architectures provide their own variants. But I am missing something somewhere as I cannot see how this builds. asm-generic now provide the fb_read/fb_write helpers. But for example sparc has an architecture specifc fb.h so it will not use the asm-generic variant. So I wonder how sparc get hold of the asm-generic fb.h file? Maybe it is obvious, but I miss it. Sam
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