Re: [PATCH] sh: clk: Fix discarding const qualifier warning

Geert Uytterhoeven
2020-01-07T13:00:41Z

Hi Krzysztof,

On Tue, Jan 7, 2020 at 1:26 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> ioreadX() accepts pointer to non-const memory. This fixes warnings
> like:
>
> drivers/sh/clk/cpg.c: In function ‘r8’:
> drivers/sh/clk/cpg.c:41:17: warning: passing argument 1 of ‘ioread8’
> discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

Thanks for your patch!

> --- a/drivers/sh/clk/cpg.c
> +++ b/drivers/sh/clk/cpg.c
> @@ -36,17 +36,17 @@ static void sh_clk_write(int value, struct clk *clk)
> iowrite32(value, clk->mapped_reg);
> }
>
> -static unsigned int r8(const void __iomem *addr)
> +static unsigned int r8(void __iomem *addr)
> {
> return ioread8(addr);
> }

Isn't the real issue that some implementations of ioreadX() take const,
while others don't?

Even the generic ones disagree:

include/asm-generic/io.h:static inline u8 ioread8(const volatile
void __iomem *addr)
include/asm-generic/iomap.h:extern unsigned int ioread8(void __iomem *);

IMHO they all should take "const volatile void __iomem *".

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