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#L35Sure, 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.
It just occured to me that these fb_read and fb_write calls are probably all wrong. The fb_ interfaces are for framebuffer I/O memory. The driver uses them to access the regular state registers. The writew() on sh is definitely different. [1]
I assume that it only works because CONFIG_SWAP_IO_SPACE [2] is not set in hp6xx_defconfig.
Best regards Thomas[1] https://elixir.bootlin.com/linux/latest/source/arch/sh/include/asm/io.h#L55 [2] https://elixir.bootlin.com/linux/latest/source/arch/sh/include/mach-common/mach/mangle-port.h#L22
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)
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