Re: [kbuild-all] Re: drivers/scsi/ncr53c8xx.c:5306:9: sparse: sparse: cast truncates bits from constant value (58f becomes 8f)

[Philip Li]

On Fri, May 15, 2020 at 12:00:26PM -0700, Matthew Wilcox wrote:
> On Sat, May 16, 2020 at 02:20:38AM +0800, kbuild test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   051e6b7e34b9bd24f46725f74994a4d3a653966e
> > commit: 06e85c7e9a1c1356038936566fc23f7c0d363b96 asm-generic: fix unistd_32.h generation format
> > date:   5 weeks ago
> 
> I don't see how that commit in any way reflects this error message.
> 
> > reproduce:
> >         # apt-get install sparse
> >         # sparse version: v0.6.1-193-gb8fad4bc-dirty
> >         git checkout 06e85c7e9a1c1356038936566fc23f7c0d363b96
> >         make ARCH=x86_64 allmodconfig
> 
> I can't even see a way to build the ncr53c8xx module with this config.
> Unless somebody reenabled EISA on x86, the only way I can see to
> still build this driver is on PA-RISC with the ZALON code.
sorry, the reproduce steps here is wrong, it is not for x86_64. We will
fix this.

> 
> >         make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> > 
> > 
> > sparse warnings: (new ones prefixed by >>)
> > 
> > >> drivers/scsi/ncr53c8xx.c:5306:9: sparse: sparse: cast truncates bits from constant value (58f becomes 8f)
> > 
> > ^1da177e4c3f41 Linus Torvalds 2005-04-16 @5306  	OUTW (nc_sien , STO|HTH|MA|SGE|UDC|RST|PAR);
> 
> This seems entirely intentional.
> 
> Something like this should do the job (whitespace damaged):
> 
> +++ b/drivers/scsi/ncr53c8xx.h
> @@ -407,7 +407,7 @@
>  
>  #ifdef CONFIG_SCSI_NCR53C8XX_NO_WORD_TRANSFERS
>  /* Only 8 or 32 bit transfers allowed */
> -#define OUTW_OFF(o, val)       do { writeb((char)((val) >> 8), (char __iomem *)np->reg + ncr_offw(o)); writeb((char)(val), (char __iomem *)np->reg + ncr_offw(o) + 1); } while (0)
> +#define OUTW_OFF(o, val)       do { writeb((char)((val) >> 8), (char __iomem *)np->reg + ncr_offw(o)); writeb((char)((val) & 0xff), (char __iomem *)np->reg + ncr_offw(o) + 1); } while (0)
>  #else
>  #define OUTW_OFF(o, val)       writew_raw((val), (char __iomem *)np->reg + ncr_offw(o))
>  #endif
> 
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