Hi Thomas,
On Wed, May 10, 2023 at 4:20 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
Am 10.05.23 um 14:34 schrieb Geert Uytterhoeven:
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>
--- 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
I know, that's why the TODO says to convert it to generic I/O.
__raw_readq() and __raw_writeq()...
It doesn't define those macros, but it generates function calls of the
same names. Follow the macros at
https://elixir.bootlin.com/linux/latest/source/arch/mips/include/asm/io.h#L357
It expands to a variety of helpers, including __raw_*().
Thanks, I forgot MIPS is using these grep-unfriendly factories...
+ *
+ * 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?
On 64-bit builds, there's __raw_readq() and __raw_writeq().
At first, I tried to do the right thing and convert MIPS to work with
<asm-generic/io.h>. But that created a ton of follow-up errors in other
headers. So for now, it's better to handle this problem in asm/fb.h.
So isn't just adding
#define __raw_readq __raw_readq
#define __raw_writeq __raw_writeq
to arch/mips/include/asm/io.h sufficient to make <asm-generic/fb.h>
do the right thing?
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
