Hi

Am 10.05.23 um 17:54 schrieb Arnd Bergmann:

On Wed, May 10, 2023, at 16:27, Thomas Zimmermann wrote:

quoted

Am 10.05.23 um 16:15 schrieb Arnd Bergmann:

quoted

On Wed, May 10, 2023, at 16:03, kernel test robot wrote:

quoted

quoted

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
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