Re: [PATCH v6 5/6] fbdev: Move framebuffer I/O helpers into <asm/fb.h>

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Hi Thomas,

On Wed, May 10, 2023 at 1:06 PM Thomas Zimmermann <tzimmermann@xxxxxxx> 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.

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.

v6:
        * fix fb_readq()/fb_writeq() on 64-bit mips (kernel test robot)
v5:
        * include <linux/io.h> in <asm-generic/fb>; fix s390 build
v4:
        * ia64, loongarch, sparc64: add fb_mem*() to arch headers
          to keep current semantics (Arnd)
v3:
        * implement all architectures with generic helpers
        * support reordering and native byte order (Geert, Arnd)

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Tested-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>

add mips fb_q()

--- a/arch/mips/include/asm/fb.h
+++ b/arch/mips/include/asm/fb.h
@@ -12,6 +12,28 @@ static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
 }
 #define fb_pgprotect fb_pgprotect

+/*
+ * MIPS doesn't define __raw_ I/O macros, so the helpers
+ * in <asm-generic/fb.h> don't generate fb_readq() and
+ * fb_write(). We have to provide them here.

MIPS does not include <asm-generic/io.h>,  nor define its own
__raw_readq() and __raw_writeq()...

+ *
+ * TODO: Convert MIPS to generic I/O. The helpers below can
+ *       then be removed.
+ */
+#ifdef CONFIG_64BIT
+static inline u64 fb_readq(const volatile void __iomem *addr)
+{
+       return __raw_readq(addr);

... so how can this call work?

+}
+#define fb_readq fb_readq
+
+static inline void fb_writeq(u64 b, volatile void __iomem *addr)
+{
+       __raw_writeq(b, addr);
+}
+#define fb_writeq fb_writeq
+#endif
+
 #include <asm-generic/fb.h>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds



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