Messages in this thread | | | Date | Thu, 11 May 2023 12:53:43 +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
Am 10.05.23 um 17:54 schrieb Arnd Bergmann: > 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
Oh, OK. I thought it's like vgafb, which grabs the fixed VGA framebuffer range.
> 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.
Thanks for looking this up. If this driver has been broken for 15 years, the correct fix is to delete it. I've meanwhile prepared the second-best fix, which is the type casting. It'll be in the next patchset.
Best regards Thomas
> > Arnd
-- 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] | |