Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Thu, 11 May 2023 14:35:51 +0200 | Subject | Re: [PATCH v6 5/6] fbdev: Move framebuffer I/O helpers into <asm/fb.h> |
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Hi Arnd,
CC Artur, who's working on HP Jornada 680.
On Wed, May 10, 2023 at 5:55 PM Arnd Bergmann <arnd@arndb.de> wrote: > On Wed, May 10, 2023, at 16:27, Thomas Zimmermann wrote: > > Am 10.05.23 um 16:15 schrieb Arnd Bergmann: > >> On Wed, May 10, 2023, at 16:03, kernel test robot wrote: > > >> I think that's a preexisting bug and I have no idea what the > >> correct solution is. Looking for HD64461 shows it being used > >> both with inw/outw and readw/writew, so there is no way to have > >> the correct type. The sh __raw_readw() definition hides this bug, > >> but that is a problem with arch/sh and it probably hides others > >> as well. > > > > The constant HD64461_IOBASE is defined as integer at > > > > > > https://elixir.bootlin.com/linux/latest/source/arch/sh/include/asm/hd64461.h#L17 > > > > but fb_readw() expects a volatile-void pointer. I guess we could add a > > cast somewhere to silence the problem. In the current upstream code, > > that appears to be done by sh's __raw_readw() internally: > > > > > > https://elixir.bootlin.com/linux/latest/source/arch/sh/include/asm/io.h#L35 > > Sure, that would make it build again, but that still doesn't make the > code correct, since it's completely unclear what base address the > HD64461_IOBASE is relative to. The hp6xx platform code only passes it > through inw()/outw(), which take an offset relative to sh_io_port_base, > but that is not initialized on hp6xx. I tried to find in the history > when it broke, apparently that was in 2007 commit 34a780a0afeb ("sh: > hp6xx pata_platform support."), which removed the custom inw/outw > implementations.
See also commit 4aafae27d0ce73f8 ("sh: hd64461 tidying."), which claims they are no longer needed.
Don't the I/O port macros just treat the port as an absolute base address when sh_io_port_base isn't set?
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
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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