Messages in this thread | | | Date | Wed, 10 May 2023 17:11:27 +0200 | Subject | Re: [PATCH v6 5/6] fbdev: Move framebuffer I/O helpers into <asm/fb.h> | From | Thomas Zimmermann <> |
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Hi Geert
Am 10.05.23 um 16:34 schrieb Geert Uytterhoeven: > Hi Thomas, > > On Wed, May 10, 2023 at 4:20 PM Thomas Zimmermann <tzimmermann@suse.de> wrote: >> Am 10.05.23 um 14:34 schrieb Geert Uytterhoeven: >>> On Wed, May 10, 2023 at 1:06 PM Thomas Zimmermann <tzimmermann@suse.de> 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@suse.de> >>>> Tested-by: Sui Jingfeng <suijingfeng@loongson.cn> >>>> Reviewed-by: Arnd Bergmann <arnd@arndb.de> > >>>> --- 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?
That works. I had a patch that adds all missing defines to MIPS' io.h. Then I went with the current fix, which is self-contained within fbdev. But I'd leave it to arch maintainers.
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) [unhandled content-type:application/pgp-signature] | |